25th International Spin Symposium (SPIN 2023)

Sep 24, 2023, 8:00 AM → Sep 29, 2023, 6:30 PM US/Eastern

Durham Convention Center

Anselm Vossen (Duke University), Thomas Mehen (Duke U.)

 

 

Update: Registration and 2nd Circular are now available

 

 

 

The 25th iteration of the International Spin Symposium (SPIN 2023) will be organized by Duke University and held September 24-29 at the Durham Convention Center. The Symposium is one of the pre-eminent venues bringing together theorists and experimentalists in the field of spin physics. It is held every two years, alternating between the U.S., Europe and Asia.

The conference series has been held jointly since 2000, combining the High Energy Spin Symposia and the Nuclear Polarization Conferences.

The most recent symposia were held in Charlotteville, VA (2008), Jülich, Germany (2010) Dubna, Russia (2012), Beijing, China (2014), Urbana Champaign, IL (2016), Ferrara, Italy (2018) and Matsue, Japan (2021).

 

The organizing committee of SPIN2023 is co-chaired by Thomas Mehen and Anselm Vossen. It can be contacted using the link on the sidebar.

The parallel session topics and conveners are listed here.

 

 

 

This project is supported by the Initiatives Fund Program, a JSA commitment, to support programs, initiatives, and activities that further the scientific outreach, promote the science, education and technology of Jefferson Lab and benefit the Lab’s extended user community in ways that complement the Lab’s basic and applied research missions.

Spin2023Plenary.pdf

Spin2023Plenary.png

Sunday, September 24

Welcome Reception

Monday, September 25

Plenary: Form Factors

Convener: Charlotte Van Hulse (IJCLab)

1 Welcome

Speaker: Anselm Vossen (Duke University/JLab)

SPIN2023_Welcome.pdf

2 Electromagnetic and gravitational form factors of the nucleon

Form factors are Lorentz invariant functions describing the internal structure of a system. In particular, they encode how physical properties like charge, energy, momentum, pressure, ... are spatially distributed. While nucleon electromagnetic form factors have been studied for a long time, the first extraction of nucleon gravitational form factors from experimental data was reported in 2018, triggering a lot of enthusiasm and attention in the hadronic community. In this talk we review some theoretical bases, discuss recent developments regarding the physical interpretation of these form factors, and give a glimpse of what can be learned about the mass and spin structure of the nucleon.

Speaker: Cedric Lorce (Ecole polytechnique)

SPIN2023.pdf

3 Gluonic Gravitational Form Factors of the Proton

The gravitational form factors (GFFs) are an elegant way to describe the structure of nucleons and nuclei. Their Fourier transform allow a a description of the spatial distribution of the mass, angular momentum , pressure and shear forces densities for both quarks and gluons in the nucleon. The GFFs have been the target of an intensive investigation at Jefferson Lab and form the basis of nucleon and nuclei partonic structure studies at the future EIC. In this talk I will focus on the recent results of $J/\psi$ production near threshold at Jefferson Lab to determine the gluonic gravitational form factors and discuss the caveats of their extraction in the threshold region. I'll also discuss the future critical complementary measurements of $\Upsilon$ at the EIC critical to access the trace anomaly and gain insight into the origin of the nucleon mass.

Speaker: Zein-Eddine Meziani (Argonne National Laboratory)

SPIN2023-Meziani.pdf

4 The Generalized Polarizabilities of the proton

The polarizabilities of a composite system such as the proton are elementary structure constants. They describe its response to an external electromagnetic (EM) field and quantify the deformation of the charge and magnetization distributions inside the proton caused by the electric or magnetic field, respectively. When studied through the virtual Compton scattering process, the virtuality of the photon gives access to the generalized polarizabilities and allows to map out the resulting deformation of the densities in a proton subject to an EM field. These measurements provide unique access to the underlying system dynamics and are a key for decoding the proton structure in terms of the theory of the strong interaction that binds its elementary quark and gluon constituents together. Of particular interest are puzzling measurements of the proton's electric generalized polarizability, that have challenged the theoretical predictions in recent years. This talk will present an overview on the topic, followed by the discussion of new results and of future prospects.

Speaker: Prof. Nikos Sparveris (Temple University)

SPIN 2023 GPs.pdf

10:30 AM Coffee Break

Plenary: Applications

Convener: Thomas Theis (NC State University)

5 Quantum Diamond Sensors — Best of Both Worlds

The nitrogen–vacancy (NV) quantum defect in diamond is a leading modality for magnetic, electrical, temperature, and pressure sensing with high spatial resolution and wide field-of-view, operating under both ambient and extreme conditions. This quantum sensing technology has diverse applications across the physical and life sciences — from probing magnetic materials to NMR of single cells, proteins, and spins. I will provide an overview of quantum diamond sensors and their many applications.

Speaker: Ronald Walsworth (University of Maryland)

6 A research program to measure the lifetime of spin polarized nuclei in magnetically confined fusion plasmas

The use of spin polarized fuel could increase D-T fusion reactivity by a factor of 1.5 and, owing to alpha heating, increase fusion Q in ITER even more [1]. The use of polarized D and 3He in an experiment avoids the complexities of handling tritium, while encompassing the same nuclear reaction spin-physics, making it a useful proxy to study issues associated with full D-T implementation. 3He fuel with 65% polarization can be prepared by permeating optically-pumped 3He into a shell pellet [1]. Dynamically polarized 7Li-D pellets can achieve 70% vector polarization for the deuterium [1]. The polarization lifetimes in cooled 3He fuel capsules are days, while only minutes for 7Li-D [1]. (This is still much greater than the ~10 second duration of a plasma shot in a research tokamak such as DIII-D.) Cryogenically-frozen pellets can be injected vertically into tokamaks by special injectors that minimize depolarizing field gradients. The use of a Sona transition [2] to polarize neutral beams is also under investigation. Theoretically [3], nuclei remain polarized in a hot fusion plasma for much longer than the particle confinement time but the predictions have never been tested experimentally. Measurements that exploit spin-induced changes in differential cross section are more sensitive than measurements of the reaction rate alone [4]. One possible experimental scenario uses an unpolarized 3He fast-ion population (~80 keV) and tensor-polarized deuterium pellets; in another, both species are polarized in a thermonuclear plasma with ion temperatures above 10 keV. Modeling shows that a Ti>10 keV DIII-D plasma generates 14.7 MeV proton and 3.6 MeV alpha signals that are sensitive to depolarization with high accuracy [4]; additionally, nearly all reactor-relevant depolarization mechanisms are accessible for study in DIII-D. With a sufficiently intense polarized beam, accurate measurements of the depolarization rate could also be performed in the Wisconsin HTS Axisymmetric Mirror. Experiments in a compact spherical tokamak are also under investigation.
[1] L.R. Baylor et al., Nucl. Fusion 63 (2023) doi 10.1088/1741-4326/acc3ae
[2] R. Engels et al., Eur. Phys. J. D 75:257 (2021).
[3] R.M. Kulsrud et al., Nucl. Fusion 26 (1986) 1443.
[4] A.V. Garcia et al., Nucl. Fusion 63 (2023) 026030.

Speaker: W.W. Heidbrink

SPIN2023Heidbrink.pdf

SPIN2023Heidbrink.pptx

7 Quantum computing QCD for hadron structure and dynamics

Quantum simulation may open the door to addressing a range of computationally intractable problems in strong-interaction physics. In particular, with its reliance on Hamiltonian methods, quantum-simulation and quantum-computing methods are ideal for accessing a wealth of static and dynamical properties of hadrons, nuclei, and dense matter, including a range of structure functions, dynamical response functions, transport properties, and non-equilibrium and thermalization physics of quantum chromodynamics. Significant progress is reported in recent years in developing theoretical foundations and algorithmic tools, and in implementing and benchmarking problems on quantum hardware. I will review some of these activities, and I will further comment on what it may take for quantum simulation to be considered a reliable and accessible approach to studying strong-interaction physics in the coming years.

Speaker: Zohreh Davoudi (University of Maryland)

QCD-QC-ZD-Sep-2023.pdf

12:30 PM Lunch Break

3D Structure of the Nucleon: GPDs and Form Factors: GPDs I

Convener: Dave Gaskell (Jefferson Lab)

8 Reconstruction of GPDs in the small x region

Perturbative evolution offers the well-identified possibility of reconstructing the skewness dependence of generalized parton distributions (GPDs) in the small Bjorken x domain. This general idea has notably been used to constrain gluon PDFs at small x from exclusive heavy meson photoproduction. We study the regime of validity and the uncertainty associated to this method. We discuss more generally the crucial role that evolution plays to guide modelling strategies of GPDs, whether from exclusive processes at small and moderate skewness or from lattice data.

Speaker: Hervé Dutrieux (College of William & Mary)

Presentation_2023_09_25__SPIN_.pdf

9 Shedding Light on Shadow Generalized Parton Distributions

The feasibility of extracting generalized parton distributions (GPDs) from deeply-virtual Compton scattering (DVCS) data has recently been questioned because of the existence of an infinite set of so-called ``shadow GPDs'' (SGPDs). These SGPDs depend on the process and manifest as multiple solutions (at a fixed scale $Q^2$) to the inverse problem that needs to be solved to infer GPDs from DVCS data. SGPDs therefore pose a significant challenge for extracting GPDs from DVCS data. With this motivation we study the extent to which QCD evolution can provide constraints on SGPDs. This is possible because the known classes of SGPDs begin to contribute to observables after evolution, and can then be constrained (at the input scale $Q^2_0$) by data that has a finite $Q^2$ range. The impact that SGPDs could have on determining the total angular momentum, pressure and sheer force distributions, and tomography is also discussed. Our key finding is that scale evolution, coupled with data over a wide range of skewness $\xi$ and $Q^2$, can constrain the class of SGPDs that we studied and potentially make possible the extraction of GPDs from DVCS data over a limited range in the GPD variables.

Speaker: Eric Moffat (Argonne National Lab)

SPIN_Moffat_9_25_23.pdf

10 The Correlated Spatial Structure of the Proton: Two-body densities as a framework for dynamical imaging

The Fourier transforms of generalized parton distributions (GPDs) give single-particle spatial densities of the quarks and gluons inside the proton. The physical properties derived from GPDs include the average radius of each partonic component of the nucleon and other quantities. To capture a fuller dynamical picture of the proton’s internal structure, information on the relative position between partons is crucial; two-particle densities give such relative positions between the quarks and gluons in the transverse plane. Connecting the two-body densities to observables, we show that two-particle densities can be defined in QCD with generalized double parton distributions (GDPDs). Using GDPDs, we can describe nucleons’ quark and gluon dynamics through overlap probabilities. Such quantities allow us to extract information from data on the geometric structure of the proton.

Speaker: Zaki Panjsheeri (University of Virginia)

SPIN_2023_correlated_Panjsheeri.pdf

11 GUMP program and GPD global analysis

I will discuss the recent progress of the generalized parton distributions (GPDs) through universal moment parameterization (GUMP) program for the global analysis of GPDs that aims to combine the experimental inputs as well as lattice simulation results for a better determination of GPDs. I will briefly report the current status of the program and also discuss the important future developments.

Speaker: Yuxun Guo (University of Maryland)

GUMP_SPIN2023.pdf

3D Structure of the Nucleon: TMDs: TMDs I

Convener: Yoshitaka Hatta (Brookhaven National Laboratory)

12 New developments in di-hadron theory and phenomenology

This presentation has two parts. We first discuss a new definition of di-hadron fragmentation functions which have an interpretation as number densities. We then present the results of our extraction of the di-hadron fragmentation functions and the transversity distributions of the nucleon, based on data for electron-positron annihilation, semi-inclusive DIS and proton-proton collisions. We compare our results to a previous analysis of the di-hadron channel and to extractions of the transversity from single-hadron production. Furthermore, we compute the tensor charge which we compare with, in particular, calculations from lattice QCD. Overall, we find that all currently available information on the transversity and the tensor charge is in agreement within errors, leading to a universal picture of these quantities.

Speaker: Andreas Metz (Physics Department, Temple University, Philadelphia)

SPIN_2023_dihadron.pdf

13 Measurements of Transverse Spin Dependent $\pi^+\pi^-$ Azimuthal Correlation Asymmetry and Unpolarized $\pi^+\pi^-$ Cross Section in $pp$ Collisions at $\sqrt s = 200$ GeV at STAR

The transversity distribution function, $h_1^{q}(x)$, encapsulates the transverse spin structure of the proton at the leading twist, where $x$ represents the longitudinal momentum fraction carried by the quark $q$. The extraction of $h_1^{q}(x)$ poses a formidable challenge due to its chiral-odd nature. Measurements of final-state di-hadron pairs in transversely polarized proton-proton ($p^\uparrow p$) collisions directly probe the collinear quark transversity via coupling with a chiral-odd interference fragmentation function, $H_1^{\sphericalangle, q}$. This coupling results in an experimentally measurable azimuthal correlation asymmetry, $A_{UT}$. The asymmetry originates from the interplay between the spin orientation of the fragmenting quark and the resulting di-hadron in the final state. Thus, it necessitates precise knowledge of unpolarized di-hadron fragmentation functions (FFs) to achieve a model-independent extraction of the transversity from these measurements. These FFs can be obtained by measuring the unpolarized di-hadron cross section in $pp$ collisions. We will present preliminary results on the $A_{UT}$ for $\pi^+\pi^-$ pairs using $p^\uparrow p$ data collected by the STAR experiment at a center-of-mass energy of $\sqrt{s} = 200$ GeV in 2015. Additionally, we will present preliminary results of the unpolarized $\pi^+\pi^-$ cross section using $pp$ data at $\sqrt{s} = 200$ GeV collected in 2012.

Speaker: Babu Pokhrel (Temple University)

Babu_XsecIFF_SPIN2023.pdf

14 Transverse Spin Dependent Azimuthal Correlations of Charged Pion Pairs in $p^{\uparrow}p$ collisions at $\sqrt{s} = 510$ GeV at STAR

The trasverse polarization of quarks within a trasversely polarized nucleon, $h^q_1(x)$, can only be accessed through processes involving its coupling with another chiral-odd functions, such as the spin-dependent interference fragmentation function (IFF) in polarized proton-proton collisions. The coupling of $h^q_1(x)$ and IFF leads to a measurable azimuthal correlation asymmetry ($A_{UT}$) of di-hadron pairs in the final state. In previous work, the STAR experiment at RHIC measured a non-zero $A_{UT}$ using polarized proton-proton ($p^\uparrow p$) data from 2011 at $\sqrt s = 500$ GeV, with an integrated luminosity of 25 pb$^{-1}$. The precise measuremnt of $A_{UT}$ together with unpolarized di-hadron cross section will help to constrain the $h^q_1(x)$ in the global fits. In 2017, the STAR experiment collected dataset of approximately 350 pb$^{-1}$ from $p^\uparrow p$ collisions at $\sqrt s = 510$ GeV. In 2022, another dataset featuring $p^\uparrow p$ collisions at $\sqrt s = 508$ GeV of an integrated luminosity of approximately 400 pb$^{-1}$ was collected. These new datasets will significantly improve the statistical precision of the $A_{UT}$ measurement. In this talk, we will present an update on the measurement of $A_{UT}$ for pion pairs in the pseudorapidity region $|\eta|<1$ based on the 2017 $p^\uparrow p$ dataset and the projection for the 2022 dataset.

Speaker: Navagyan Ghimire (Temple University, Philadelphia, PA, USA)

SPIN2023_final_Navagyan.pdf

15 Top quark polarization and gluon spin and transversity in the nucleon

Top quark polarization and gluon spin and transversity in the nucleon
G. Goldstein
Top pair production at LHC is a prime example that proceeds primarily via gluon fusion. Decays of polarized top pairs through various channels produce a variety of correlations among the decay products - particles and jets. Combinations of the gluon distributions, either polarized or unpolarized, can be accessed experimentally through angular dependences of decay products, as will be shown, along with predictions from a spectator model of gluon distributions.

Speaker: Prof. Gary Goldstein (Tufts University)

SPIN2023_Goldstein_b.pdf

16 Azimuthal transverse single-spin asymmetries of inclusive jets and hadrons within jets from polarized ${pp}$ collisions at $\sqrt{s}$ = 510 GeV

The study on the origin of transverse single-spin asymmetries has triggered the development of the twist-3 formalism and the transverse-momentum-dependent parton distribution functions (TMDs) .
Measurement of the azimuthal distribution of identified hadrons within a jet in transversely polarized hadronic interactions provides an opportunity to study the TMD physics, such as the Collins effect which involves the quark transversity and the Collins fragmentation functions.
STAR has reported measurements of Collins asymmetries from jet + $\pi^{\pm}$ production in transversely polarized ${pp}$ collisions at a center-of-mass energy of $\sqrt{s}$ = 500 GeV, based on data taken in 2011 with an integrated luminosity of 23 $\mathrm{pb}^{-1}$. Additionally, an extensive measurement of azimuthal transverse single-spin asymmetries of inclusive jets and hadrons within jets from transversely polarized ${pp}$ collisions at $\sqrt{s}$ = 200 GeV was performed using data from 2012 and 2015.
In 2017, STAR collected a significantly larger ${pp}$ dataset with an integrated luminosity of 350 $\mathrm{pb}^{-1}$ at $\sqrt{s}$ = 510 GeV, which will further improve the precision of the transverse single-spin asymmetry measurements especially at high jet transverse momentum region.
In this talk, we will report the analysis status of azimuthal transverse single-spin asymmetries for inclusive jets and charged pions within jets from transversely polarized ${pp}$ collisions at $\sqrt{s}$ = 510 GeV.

Speaker: Yixin Zhang (Shandong University)

SPIN2023_YixinZhang.pdf

Fundamental Symmetries and Spin Physics Beyond the Standard Model: Fundamental Symmetries I

17 Selected results on the electric dipole moments from lattice QCD

After a brief summary of the current status for experimental searches of a permanent electric dipole moments, I delve into the various sources of CP-violation and the computational challenges associated with calculating the corresponding hadronic matrix elements using the lattice as a regulator. I then proceed detailing recent results obtained
on the neutron EDM highlighting the primary theoretical and numerical tool employed: the gradient flow. By leveraging this approach, I showcase significant progress made in understanding the neutron EDM.
I conclude outlining the near-term objectives, addressing the challenges lying ahead, and providing an optimistic outlook for the future of EDM research.

Speaker: Andrea Shindler

shindler_edm.pdf

2:20 PM Discussion

18 Neutron Electric Dipole Moment from Isovector Quark Chromo-Electric Dipole Moment

We share results from our lattice QCD study of the contribution of the isovector quark chromo-electric dipole moment (qcEDM) operator to the nucleon electric dipole moments (nEDM). The calculation was done on four 2+1+1-flavor of highly improved staggered quark (HISQ) ensembles employing Wilson-clover quarks to construct correlation functions. We employ the non-singlet axial Ward identity including corrections up to O(a) to show how to control the power-divergent mixing of the isovector qcEDM operator with the lower dimensional pseudoscalar operator. Preliminary results for the nEDM due to qcEDM are presented after conversion to the MSbar scheme at the leading-log order.

Speaker: Jun-Sik Yoo (Los Alamos National Laboratory)

Talk__for_SPIN_2023-1.pdf

2:45 PM Discussion

19 The neutron electric dipole moment search at Los Alamos National Laboratory

Searches for a nonzero neutron electric dipole moment (nEDM) are probes
of new sources of time reversal symmetry violation and may give clues to
the puzzle of the matter-antimatter asymmetry of the universe. This talk
will present an overview and status of the nEDM experiment under
development at the Los Alamos National Laboratory (LANL). Using the
upgraded ultracold neutron source, the experiment targets a measurement
uncertainty of $10^{-27} e\text{ cm}$. Some of the findings during the present
commissioning of major components of the apparatus will be described.

Speaker: Douglas Wong

Spin 2023.pptx

3:10 PM Discussion

20 Measurement of the deuteron electric dipole moment using a storage ring

The search for Electric Dipole Moments (EDMs) of elementary particles is a powerful tool for the investigation of physics beyond the Standard Model (SM) of Particle Physics. As a permanent EDM violates $CP$ symmetry, measuring the EDM of a fundamental particle is a potential source of $CP$-violation that could, e.g., explain the matter-antimatter asymmetry in the universe.
Storage rings enable the measurement of charged particles EDMs by observing the effect of the EDM on the particle's spin motion in the ring. The Cooler Synchrotron COSY at the Forschungszentrum Jülich provides polarized protons and deuterons with momenta up to 3.7 GeV/s. This makes it an ideal choice for the initial stage of the JEDI (Jülich Electric Dipole moment Investigations) research program, where the JEDI collaboration aims to conduct a proof-of-principle experiment. Due to the smallness of the EDM effect and the complexity of storage rings, this study demands high precision in measurements and a thorough understanding of systematics.
In this talk, I will present the details of the analysis of the first direct precursor measurement of the deuteron EDM in COSY, discuss the various technical developments, and show recent results.

Speaker: Vera Shmakova (GSI Helmholtzzentrum für Schwerionenforschung)

shmakova_spin2023.pdf

3:35 PM Discussion

Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy I

Conveners: Annika Thiel (HISKP, Uni Bonn), Annika Thiel (HISKP Bonn)

21 Beam normal single-spin asymmetry in electron-proton scattering with intermediate state resonances

We calculate the beam normal single-spin asymmetry $B_n$ in electron--proton elastic scattering from two-photon exchange amplitudes with resonance intermediate states of spin-parity $1/2^\pm$ and $3/2^\pm$ and mass $W < 1.8$ GeV. The latest CLAS exclusive meson electroproduction data are used as input for the transition amplitudes from the proton to the excited resonance states. The spin 3/2 resonances dominate by an order of magnitude over the spin 1/2 states. In general we observe cancellations between the negative contributions of the $\Delta(1232)$ and $N(1520)$ across both beam energy and scattering angle, and the positive contributions of the $\Delta(1700)$ and $N(1720)$, leading to a rather large overall uncertainty band in the total $B_n$. At forward angles and beam energies $E_\textrm{lab}<1$ GeV, where the $\Delta(1232)$ dominates, the calculated $B_n$ tend to overshoot the A4 and SAMPLE data.
The calculated $B_n$ compare well with the measured values from the A4 and $Q_{\textrm{weak}}$ experiments with $E_\textrm{lab}>1$ GeV.

Speaker: Dr Peter Blunden (University of Manitoba)

SPIN2023_Blunden.pdf

22 Systematic studies of beam-normal single spin asymmetries at MAMI

Pushing the precision frontiers further in nuclear physics brings up new experimental challenges as well as the demand for more sophisticated theoretical calculations. Especially in parity- violation electron scattering experiments, the contribution from higher order processes, such as two-photon exchange, is comparable in size with the observed asymmetry $A_{PV}$. Hence, a precise knowledge of this contribution is mandatory to determine the systematic uncertainties.
Beam-normal single spin asymmetries $A_{n}$ (or the so-called transverse asymmetries) are a direct probe of the imaginary part of the two-photon exchange amplitude in the elastic scattering of transversely polarized electrons from unpolarized nucleons. Up to now, there is significant disagreement between experiment and theory for $^{208}$Pb, which motivates more measurements to study the Q$^{2}$ and Z dependence. During a successful campaign at the MAinz MIcrotron (MAMI) using the spectrometer setup of the A1 collaboration, the Q$^{2}$ dependence of $A_{n}$ for $^{12}$C was determined. The follow-up experiments on $^{28}$Si and $^{90}$Zr investigated the charge dependence of the transverse asymmetry and have paved the way for a future experiment on $^{208}$Pb, thus benchmarking the theoretical calculations in the heavier mass regime.

Speaker: Michaela Thiel

MThiel_TransverseAsymmetry_SPIN2023.pdf

23 Single spin asymmetries in electron-nucleon scattering at low and intermediate energies

Normal spin asymmetries are an important tool in the study of hadron structure. They can be studied in a wide range of reactions in electron scattering, namely elastic, inclusive, semi-inclusive, and a wide range of energies. Experimental results are still few and far apart. Theoretical means of study are still limited, with the low energy purely elastic case being the only one under almost complete control. In this talk we cover the next stage beyond that case, where the Delta resonance can be excited, and up to energies close to the next higher resonance. This regime is amenable to an approach that uses the 1/Nc expansion to unify the description of the EM interaction for nucleons and Delta, and where effects can be organized in powers of 1/Nc. The target single spin asymmetry is then studied to the next subleading order in 1/Nc. It is expected that the results are predictions accurate to that order, and can motivate efforts to mesure the asymmetry in the low/intermediate energy regime where there are no significant results.

Speaker: Prof. Jose Goity (Hampton University and Jefferson Lab)

TALK-SPIN2023-GOITY-9-25-23.pdf

Nucleon Helicity Structure: Helicity I

Convener: Andrey Tarasov (North Carolina State University)

24 Constraining the quark and gluon helicity at STAR

How do quarks and gluons conspire to provide the total spin of proton is a long-standing puzzle in quantum chromodynamics (QCD). The unique capability of RHIC, that can provide longitudinally polarized $p+p$ collisions at both $\sqrt{s} = 200$ GeV and $\sqrt{s} = 510$ GeV, opened new territory to constrain the helicity structure of the proton with unprecedented depth and precision.

Results from various STAR spin measurements have contributed significantly to our understanding of the quark and gluon helicity distributions inside the proton. The longitudinal double-spin asymmetry, $A_{LL}$, from the STAR 2009 inclusive jet measurement, provides the first indication of the positive gluon polarization with partonic momentum fraction $x$ greater than 0.05 inside the proton. More precise measurements using the $p+p$ data collected in 2012, 2013 and 2015 at both $\sqrt{s}$ = 510 and 200 GeV confirm the previous findings and provide additional constraints in the largely unexplored region of $x < 0.05$. Compared to the inclusive jet observables, analyses of dijet production extending to higher pseudorapidity (up to $\eta \sim 1.8$) provide better constraints on the $x$ dependent behavior of $\Delta g(x)$. Moreover, the reconstruction of $W^{\pm}/Z$ in longitudinally polarized proton-proton collisions provides significant constraints on the flavor separation of the light sea quark helicity distributions inside the proton, while the longitudinal spin transfer to $\Lambda$ and $\bar \Lambda$ hyperons provides access to the helicity of strange and anti-strange quarks in the proton.

In this talk, an overview of recent results on longitudinal spin structure of the proton from STAR as well as their impact on global analysis of helicity distributions will be presented.

Speaker: Ting Lin (Shandong University)

SPIN2023_TingLin_20230920.pdf

25 Spin observables in Deep Processes with CLAS12 at Jefferson Lab

Run Group C (RGC) is a series of Electron-nucleon scattering experiments sensitive to target- and double-spin observables. It has been recently performed with the CLAS12 spectrometer in Hall B at Jefferson Lab. The experiments scattered highly polarized 11 GeV electrons by longitudinally polarized proton/neutron targets, a first with the newly upgraded CLAS12. In this presentation, we overview the physics program of the experiment, the experimental setup, and the data collection/processing timeline. We also report on several ongoing analyses: single- and double-spin asymmetries in Deeply Virtual and Timelike Compton Scattering (DVCS and TCS) as well as Semi-Inclusive (SIDIS) and Inclusive (DIS) scattering on the proton and the deuteron/neutron.

Speaker: Mr Gregory Matousek (Duke University)

Matousek_SPIN2023.pdf

26 Measurement of the Neutron Spin Asymmetry in the Deep Valence Quark Region

After decades of study of the nucleon spin structure, the deep-valence quark (high x) region remains difficult to access experimentally. On the other hand, the deep valence quark region is is a clean testing ground of various predictions for the ratio of polarized and unpolarized structure functions, and quark polarization inside the proton. These predictions include relativistic constituent-quark model, perturbative QCD, light-cone holographic QCD, and Schwinger-Dyson equations. We report on a 12 GeV Jefferson Lab experiment (E12-06-110) that measured the virtual photon asymmetry of the neutron, A1n. The experiment used a longitudinally polarized beam of 10.4 GeV energy and a polarized 3He target in Hall C. It pushed the highest x value from x=0.61 of the 6 GeV era to x=0.75. Preliminary results and the current status of the analysis will be presented.

(the author is giving this talk on behalf of the E12-06-110 Collaboration)

– This work is supported in part by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract number DE–SC0014434.

Speaker: Xiaochao Zheng (University of Virginia)

talk_A1n_Spin2023.pdf

Polarized Ion and Lepton Sources and Targets: Sources and Targets I

Convener: Erdong Wang (BNL)

27 Surface protection photocathode for spin electron source

Currently, GaAs-based photocathodes with CsO activation layer serve as the practical source of polarized electrons. However, a thin CsO layer is susceptible to vacuum poisoning. Recent studies have shown that graphene, when applied as a thin layer, can effectively hinder the reaction between reactive gas molecules like oxygen and carbon dioxide. However, the deposition of a monolayer 2D material onto GaAs based photocathodes presents a significant challenge due to the stringent vacuum requirements. The incorporation of a novel technique called intercalation offers a solution to this issue, as alkali atoms can pass through defects in a graphene thin film to create photocathodes with a monolayer graphene protection layer on top. The utilization of the intercalation process for fabricating alkali-based photocathodes with graphene protection shows great promise. In this work, we will present our advancements in incorporating a graphene-based protection layer on different photocathodes.

Speaker: Jyoti Biswas (Brookhaven National Laboratory)

SPIN23__Biswas.pdf

28 Strained Superlattice photocathode development using CBE and MBE

Researchers at University of California Santa Barbara and Jefferson Lab investigated growth of high polarization heterostructure GaAs photocathodes using either chemical- or molecular-beam epitaxy (CBE or MBE). High polarization photocathodes are required to generate electron beams for particle accelerator physics experiments, and there is an urgent need to to re-establish a source of high polarization photocathode material. Due to the typical challenges for growing "standard" GaAs/GaAsP photocathodes in an MBE or CBE system, the UCSB team began investigating InAlGaAs/AlGaAs, which has been demonstrated as a candidate for high spin polarization and high quantum efficiency (QE). Several variations on InAlGaAs/AlGaAs superlattice photocathodes with varied In and Al content, including those with distributed Bragg reflector (DBR) structures to enhance QE, were grown and tested. Promising results of spin polarization of 80% and QE of 0.3% will be presented.

Speaker: Marcy Stutzman (Jefferson Lab)

Stutzman SPIN2023_final.pdf

29 Spin polarized electron beams production beyond III-V semiconductors

The talk will summarize the state of the art of photocathode based on III-V semiconductor for spin polarized electron beam production and illustrate the limitations that have prevented this class of materials to provide a long term reliability at the highest average beam currents necessary for some of the new accelerator facilities or proposed upgrades of existing ones.
This points to the need of studying and exploring alternative classes of materials that have shown properties that can be leveraged to produce photocathodes that can potentially outperform III-V semiconductors for the production of spin polarized electron beams and support the operating conditions of advanced electron sources for new facilities.

Speaker: Luca Cultrera (Brookhaven National Laboratory)

Cultrera-SPIN2023.pptx

Spin in Heavy Ion Collisions: Heavy Ions I

Convener: Aihong Tang (Brookhaven National Laboratory)

30 Hyperon polarization measurements in heavy-ion collisions (invited abstract)

In non-central heavy-ion collisions, an initial orbital angular momentum carried by two colliding nuclei is partially transferred to the created medium, resulting in polarization of produced particles on average along the direction of the orbital angular momentum. The observation of global polarization opens new directions in the study of heavy-ion physics. Since the discovery of $\Lambda$ global polarization by STAR Collaboration, a lot of progress has been made in both experimental and theoretical sides. Also, non-trivial collective velocity field due to anisotropic flow leads to vorticity, and therefore local polarization, along the beam direction. Theoretical models based on thermal vorticity fail to describe the local polarization in its sign, which is under intense discussion. In this talk, recent results on global and local polarization of hyperons in heavy-ion collisions will be discussed.

Speaker: Takafumi Niida (University of Tsukuba)

SPIN2023-niida.pdf

31 Measurements of Global and Local Polarization of Hyperons in 200 GeV Isobar Collisions from STAR

In heavy-ion collisions, the observation of the global and local polarization of hyperons has revealed the existence of large vorticities perpendicular to reaction plane due to systems's orbital angular momentum and along beam direction due to collective velocity field, respectively. With the high-statistics data from isobar collisions of Ru+Ru and Zr+Zr at $\sqrt{s_{NN}}= 200$ GeV collected by the STAR experiment, we present differential measurements of global polarization for $\Lambda$, $\bar{\Lambda}$ and $\Xi^{\pm}$ as a function of centrality, $p_{T}$, $\eta$ and azimuthal angle relative to the first order event plane.
These measurements allow us to study possible magnetic field driven effects through the polarization difference between Ru+Ru and Zr+Zr, owing to a larger magnetic field in the former. Furthermore, the first measurements of $\Lambda$ hyperon local polarization along the beam direction relative to the third order event plane as well as the second order event plane will be presented.
Comparisons with previous measurements at RHIC and the LHC provides important new insights into the collision system size or energy dependence of the vorticities in heavy-ion collisions.

Speaker: Xingrui Gou (Shandong University)

SPIN2023_Xingrui_v4.pdf

32 Spin polarization in heavy-ion collisions induced by thermal vorticity and thermal shear

By measuring the spin polarization of hadrons produced in heavy-ion collisions, it was found that the quark gluon plasma is the most "vorticous" fluid ever observed. This opens the possibility for new phenomenological investigations of spin physics in fluids. Spin polarization is mainly caused by the spin-rotation coupling in relativistic hydrodynamics. In this talk I show how the mean spin polarization vector can be computed starting from a notion of local thermal equilibrium which is compatible with quantum field theory. I show that spin polarization induced by thermal vorticity is related to the form factor related to spin-rotation coupling and that also the shear flow of the fluid contributes to spin polarization. Furthermore, I will also discuss how pseudo-gauge transformations affect the predictions of spin polarization.

Speaker: Matteo Buzzegoli (Iowa State University)

Buzzegoli_Spin_symposium_2023.pdf

33 Collective dynamics of polarized spin-half fermions in relativistic heavy-ion collisions

Standard relativistic hydrodynamics, through the years, has been extremely successful in describing the properties of the strongly-interacting matter produced in heavy-ion collision experiments. Recently, there has been a significant theoretical advancement in this field to explain a new phenomenon of spin polarization of hadrons emitted in these processes. Although current models have successfully explained some of the experimental data based on the coupling between spin polarization and the vorticity of the medium, they still lack a clear understanding of the differential measurements. This is commonly interpreted as an indication that the spin needs to be treated as an independent degree of freedom whose dynamics is not entirely bound to flow circulation. In particular, if the spin is a macroscopic property of the system, in equilibrium its dynamics should follow hydrodynamic laws. In this thesis, we develop a framework of relativistic perfect-fluid hydrodynamics which includes spin degrees of freedom from the quantum kinetic theory for Dirac fermions and use it for modeling the dynamics of matter produced in relativistic heavy-ion collisions. Following experimental observations, we assume that the polarization effects are small and derive conservation laws for the net-baryon current, the energy-momentum tensor, and the spin tensor based on the so-called de Groot--van Leeuwen--van Weert definitions of these currents. Subsequently, we present various properties of the spin polarization tensor and its components, analyze the propagation properties of the spin polarization components, and derive the spin-wave velocity for arbitrary statistics. We find that only the transverse spin components propagate, analogously to the electromagnetic waves. Finally, using our hydrodynamic framework, we study the spacetime evolution of the spin polarization for the systems respecting certain spacetime symmetries and calculate the mean spin polarization per particle, which can be compared to the experimental data. We find that, for some observables, our spin polarization results agree qualitatively with the experimental findings and other model calculations. Considering the importance of electromagnetic fields in heavy-ion collisions, we also analyze the effect of external electric fields on the dynamics of spin polarization in the Bjorken-expanding background.

Speaker: Rajeev Singh (Center for Nuclear Theory, Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA)

SPIN2023_Rajeev_Singh.pdf

3:40 PM Coffee Break

3D Structure of the Nucleon: GPDs and Form Factors: GPDs II

Convener: Lubomir Pentchev (Jefferson Lab)

34 GPD measurements at COMPASS

Deeply virtual Compton scattering (DVCS) and deeply virtual meson production (DVMP) are well known to provide access to the generalised parton distributions (GPDs) of the nucleon. The COMPASS collaboration at CERN studied them in 2012, 2016 and 2017 using a 160 GeV $\mu^+$ and $\mu^-$ beam and a liquid hydrogen target. The beam was longitudinally polarised in opposite directions depending on the muon charge. The exclusivity of the reaction was ensured by a recoil proton detector, while the acceptance for photons from the DVCS or from $\pi^0$ decay was improved
adding a large-angle electromagnetic calorimeter to the COMPASS setup.
We will review the results for the DVCS cross-section and its $|t|$-dependence, which is mainly sensitive to the GPD $H$ and to the transverse extension of partons in the proton, the exclusive $\pi^0$ cross-section and the spin density matrix elements of exclusive vector mesons, which could both constrain in particular the chiral-odd (“transversity”) GPDs. We will also summarize the further prospects of the analysis of these unique data.

Speaker: Jan Matoušek (Charles University (Prague, CZ))

Matousek_20230925.pdf

35 Beam-spin asymmetries in exclusive meson production at CLAS/CLAS12

Speakers: Kyungseon JOO (University of Connecticut), Kyungseon Joo (University of Connecticut)

SPIN Talk 2023 JOO.pdf

36 Exploring the gravitational structure of the proton with the dilepton final state using the CLAS12 detector at Jefferson Lab: from Timelike Compton Scattering to near-threshold J/Psi photoproduction

The Gravitational Form Factors (GFFs) give access to the internal distributions of mass, pressure and shear force inside the proton. They were considered experimentally unmeasurable for decades due to the very weak gravitational interaction. The Generalized Parton Distributions (GPDs), which describe the correlations between the longitudinal momentum and the transverse position of the partons inside the nucleon, have lately been related to the GFFs. For the first time, this relation gives the opportunity to extract GFFs experimentally. In this talk, I will present two ways to access GFFs using data taken in 2018 by the CLAS12 detector with a 10.6 GeV electron beam impinging on a liquid-hydrogen target. First, I will present the first measurement of the Timelike Compton Scattering reaction (the hard photoproduction of a lepton pair), that gives access to the quark GFFs via the angular asymmetry of the electron/positron pair. I will then present the current effort to extract the near-threshold J/ψ photoproduction cross section using the same dataset. This later measurement is expected to provide direct insight on the gluons GFFs of the proton.

Speaker: Pierre Chatagnon (Jefferson Lab)

Slides_Spin2023_Chatagnon.pdf

37 Exploring Meson Structure at Jefferson Lab

Electron scattering experiments sensitive to meson structure are made challenging by the lack of free meson targets. Experiments at Jefferson Lab make use of the nucleon's intrinsic meson cloud to study both the elastic and inelastic structure of pions and kaons. In experimental Hall C a program of exclusive pion electroproduction measurements (E12-19-006) will measure the t-dependence of the longitudinal cross section to extract the charged pion elastic form factor. Similar measurements (E12-09-011) will explore the possibility of accessing the kaon elastic form factor. A dedicated setup (using a large acceptance electron spectrometer with a recoil TPC) aims to tag recoiling nucleons to extract the meson inelastic structure function (C12-15-006). This talk will discuss the status of the pion and kaon electroproduction experiments as well as plans for the inelastic meson structure function experiment.

Speaker: Dave Gaskell

meson_structure_at_jlab_SPIN23.pdf

3D Structure of the Nucleon: TMDs: TMDs II

Convener: Andreas Metz (Physics Department, Temple University, Philadelphia)

38 Semi-inclusive diffractive deep inelastic scattering at small-x

We propose semi-inclusive diffractive deep inelastic scattering (SIDDIS) to investigate the gluon tomography in the nucleon and nuclei at small-x. The relevant diffractive quark and gluon parton distribution functions (DPDF) can be computed in terms of the color dipole S-matrices in the fundamental and adjoint representations, respectively.

Speaker: Yoshitaka Hatta (Brookhaven National Laboratory)

SPIN-TMD.pdf

39 Production of Polarized $J/\psi$ in NRQCD

We calculate the production of polarized $J/\psi$ to probe the transverse momentum dependent (TMD) quark and gluon PDFs in the proton. Within the TMD framework we calculate the 18 leading order fragmentation functions for light quarks fragmenting to a $J/\psi$, considering all possible parton and hadron polarizations. We also calculate the production of $J/\psi$ from photon-gluon fusion within the collinear factorization framework. We use non-relativistic QCD (NRQCD) to write the cross sections in terms of perturbative coefficients and non-perturbative NRQCD matrix elements. We then make predictions for semi-inclusive deep inelastic scattering cross sections relevant for the future Electron Ion Collider, identifying the different kinematic regions where each production mechanism dominates.

Speaker: Marston Copeland (Duke University)

Polarized Jpsi Production in the TMD framework SPIN.pdf

40 Transverse Single Spin Asymmetry for Inclusive and Diffractive Electromagnetic Jets at Forward Rapidity in p^{\uparrow}+p Collisions at \sqrt{s} = 200 GeV and 510 GeV at STAR

In recent decades, there have been numerous efforts to understand the origin of the unexpectedly large transverse single spin asymmetry ($A_{N}$) of inclusive hadron productions at forward rapidities observed in $p^{\uparrow}$+$p$ collisions at different center-of-mass energies ($\sqrt{s}$). Several theories have been proposed to explain this phenomenon, including the twist-3 contributions in the collinear factorization framework, the transverse-momentum-dependent contributions from the initial-state quark and gluon (Sivers functions), and/or final-state Collins fragmentation functions. However, there are indications that diffractive processes might also contribute to the large $A_{N}$, based on the previous analyses of $A_{N}$ for forward $\pi^{0}$ and electromagnetic jets (EM-jets) in $p^{\uparrow}$+$p$ collisions at STAR [1]. A direct measurement of the $A_{N}$ of diffractive processes could shed more light on the origin of the large $A_{N}$.

The STAR experiment provides an ideal opportunity to measure the $A_{N}$ for the diffractive processes at the forward rapidities with the data collected from Forward Meson Spectrometer and Roman Pot detectors. This talk will present the analysis updates and preliminary results on $A_{N}$ for inclusive and diffractive EM-jets at forward rapidity ($2.6 < \eta < 4.2$) using $p^{\uparrow}$+$p$ collisions at $\sqrt{s} =$ 200 GeV and 510 GeV at STAR. The $A_{N}$ for photon multiplicity-dependent EM-jets in the inclusive and diffractive processes will be explored, and the contribution of $A_{N}$ from diffractive processes to the inclusive processes will be discussed.

[1] (STAR) J. Adam et al., Phys. Rev. D 103, 092009 (2021)

Speaker: Xilin Liang (University of California, Riverside)

Liang_SPIN_2023.pdf

41 Transverse Single-Spin Asymmetries of Midrapidity $\pi^{0}$ and $\eta$ mesons in 200 GeV $p^{\uparrow}$ + Au and $p^{\uparrow}$ + Al Collisions at PHENIX

Understanding the spin structure of the proton is of large interest to the nuclear physics community and it is one of the main goals of the spin physics program at the Relativistic Heavy Ion Collider (RHIC). Measurements from data taken by the PHENIX detector with transverse ($p^{\uparrow}$ + $p$, $p^{\uparrow}$ + Al, $p^{\uparrow}$ + Au) proton polarization play an important role in this, in particular, due to the leading order access to gluons in polarized protons. Transverse single-spin asymmetries (TSSAs) provide insight into initial and final state spin-momentum and spin-spin parton-hadron correlations. In addition to possible final state contributions, $\pi^{0}$ and $\eta$ TSSAs access both quark and gluon correlations in the polarized proton. Furthermore, the $p^{\uparrow}$ + $A$ data from RHIC provides an opportunity to study the effect of TSSAs in the presence of additional nuclear matter. Midrapidity $\pi^{0}$ and $\eta$ mesons are measured at PHENIX by detecting the 2$\gamma$ decay with the electromagnetic calorimeter (EMCal) in the central arm spectrometer, which has fine granularity for the resolution of separate decay photons. New results for TSSAs of midrapidity $\pi^{0}$ and $\eta$ mesons in $\sqrt{s_{NN}} = 200$ GeV $p^{\uparrow}$ + Au and $p^{\uparrow}$ + Al collisions from the 2015 running year will be presented, and compared with the recent $\sqrt{s} = 200$ GeV $p^{\uparrow}$ + $p$ results.

Speaker: Dillon Fitzgerald (University of Michigan)

FitzgeraldSPIN2023.pdf

42 Transverse Single Spin Asymmetries of hadrons at forward and backward rapidities from $p^{\uparrow}+p$, $p^{\uparrow}+\mathrm{Al}$, and $p^{\uparrow}+\mathrm{Au}$ collisions in PHENIX

Studying transverse single-spin asymmetries (TSSAs) in transversely polarized proton-proton collisions ($p^{\uparrow}+p$) allows us to understand the spin structure of the proton and parton dynamics within the proton. The Relativistic Heavy Ion Collider (RHIC) is a unique apparatus for exploring the nucleon spin structure by colliding polarized protons and protons on ions ($p^{\uparrow}+A$). The measurement of TSSA of light hadrons in polarized pp and polarized pA collision can provide insight into the underlying mechanism of the TSSA. Also, measuring TSSA of open heavy flavor offers a unique opportunity to get information on the trigluon correlation function in the collinear factorization framework.
In this presentation, recent results of TSSAs for positively and negatively charged hadrons at forward and backward rapidity ($1.4<|\eta|<2.4$) over the transverse momentum $1.5

Speaker: Jeongsu Bok (Pusan National University)

Fundamental Symmetries and Spin Physics Beyond the Standard Model: Fundamental Symmetries II

43 Transverse single-spin asymmetries as a probe of anomalous dipole moments

We discuss the use of transverse single-spin asymmetries (SSAs) at a future EIC as a probe of beyond the Standard Model (SM) physics. Our calculation uses the SM Effective Field Theory framework. We show that transverse SSAs at an EIC can provide complementary probes of the same parameters responsible for anomalous electric and magnetic dipole moments of both leptons and quarks, and may help resolve some of the puzzles that current experimental measurements of these quantities pose.

Speaker: Frank Petriello (Northwestern University &amp; Argonne National Laboratory)

Petriello-SPIN2023.pdf

4:20 PM Discussion

44 Spin-Dependent Fifth-Force Search and Measurement of Compensated Ferrimagnetism in Terbium Iron Garnet using Neutron Spin Echo Spectroscopy and Neutron Radiography

Rare-earth iron garnets constitute a model system for Néel ferrimagnetism. These materials exhibit temperature-dependent orbital cancellation of the magnetism associated with the electron spins, leaving a dense ensemble of polarized electrons which are of interest as a source for exotic spin-dependent fifth-force searches. We have conducted two novel investigations of a ferrimagnetic terbium iron garnet (Tb$_{3}$Fe$_{5}$O$_{12}$) sample: one using neutron spin echo spectroscopy, the other using neutron radiography. In contrast to measurements of external fields, neutrons can probe the internal state of the ferrimagnet and determine if the cancellation of moments occurs at the unit cell level or is an emergent property as a result of compensation among inhomogeneously-distributed domains. The use of polarized neutrons in both of these techniques enabled a search for exotic interactions between the polarized electrons in the sample and incident neutrons. We describe the sample characterization, the apparatus used, as well as preliminary results.

Speaker: Caleb Hughes (Indiana University)

SPIN23_Submitted.pptx

4:45 PM Discussion

45 Helicity of Relic Neutrinos

Neutrinos in the early Universe decoupled essentially in helicity eigenstates. As they propagate through the Universe, their helicities could be modified via two effects. First, neutrinos with a finite magnetic moment would rotate their spins with respect to their momenta as they encounter cosmic magnetic fields, modifying their helicities. Second, the bending of neutrino's spin by a gravitational field lags the bending of its momentum, again modifying its helicity. We calculate both effects and investigate the implications of the helicity modification on the detection of relic neutrinos using the Inverse Tritium Beta Decay (ITBD) reaction. We find that the ITBD rate depends sensitively on the neutrino mass hierarchy and on the Dirac or Majorana nature of the neutrinos.

Speaker: Jen-Chieh Peng (University of Illinois at Urbana-Chamapign)

SPIN2023_peng.pdf

5:10 PM Discussion

46 Origin of spin in non-relativistic quantum physics

Spin is one of the intrinsic properties of the fundamental particles. Yet we know very little about the fundamental origin of spin. The model of an electron as a spinning charged sphere, which could explain its magnetic moment, does not work due to its clash with the special theory of relativity. As such, we accept the formulation of spin based on the Dirac equation. But it is experimentally known that spin exists even in non-relativistic quantum physics.

In this work, we explore the origin of spin using a semi-classical model of the angular momentum field. From the fact that the angular momentum can be expressed as the angular gradient of classical action, we deduce a wave equation in angular space, in which the spin can be viewed as the source charge of the angular momentum field. We further use it to deduce the spin quantum number for particles and fields. Finally, we check consistency with known experimental results and theoretical formulation.

Speaker: Kolahal Bhattacharya (St. Xavier's College (autonomous), Kolkata)

SPIN2023_talk.pdf

5:35 PM Discussion

Joint Helicity/Future: Joint Helicity/Future I

Convener: Patrizia ROSSI (JEFFERSON LAB)

47 Proton Spin at EIC

Spin is a unique probe for unraveling the internal structure and QCD dynamics of nucleons. One of the main questions of modern nuclear physics is how the spin of the proton originates from its quark, anti-quark, and gluon constituents and their dynamics. The EIC, being the first polarized electron-proton collider, will venture into unexplored areas in spin physics, utilizing deep inelastic scattering (DIS) as a probe of the proton's internal structure.

Apart from probing the quark sector, the EIC's broad range of $Q^2$ will allow for the investigation of scaling violations in the $g_1$ structure function, providing substantial constraints on the gluon helicity down to momentum fractions of about $x = 10^{−4}$. Additionally, the semi-inclusive DIS measurements at the EIC that detect pions and kaons, in addition to the scattered electron, will significantly enhance access to sea quark helicities compared to inclusive DIS measurements.

In my talk, I will present the perspectives on the longitudinal spin structure of the proton from the EIC, including selected aspects of the ePIC detector crucial in achieving this physics goal.

Speaker: Maria Zurek (Argonne National Laboratory)

Spin23-Zurek-EICProtonSpin.pdf

48 Exploring Quark Helicity Distributions with a 22 GeV Beam at Jefferson Lab

Quark helicity distributions play a crucial role in our understanding of the strong force and nucleon structure. An upgrade of Jefferson Lab's electron beam from 11 to 22 GeV would provide a unique opportunity to advance our understanding of quark helicity distributions, allowing us to probe at higher $Q^2$ and $x_{Bj}$ than ever before. In this talk, I will present an exploratory study of the impact such an upgrade would have on our knowledge of the nucleon spin structure and quark helicity distributions.

Speaker: Cameron Cotton (University of Virginia)

cotton_spin2023.pdf

49 Spectator tagging with polarized deuteron at EIC

Detection of the spectator nucleon in high-energy electron-deuteron scattering ("spectator tagging") controls the nuclear configuration during the high-energy process and permits a differential analysis of nuclear effects. In scattering on the polarized deuteron, spectator tagging effectively controls the spin structure of the nuclear configuration, by fixing the S/D wave ratio through the measured spectator momentum. This can be used to control the effective neutron polarization in neutron spin structure extraction from scattering on a vector-polarized deuteron, or to maximize the tensor-polarized asymmetries in scattering on a tensor-polarized deuteron. We summarize the theory and applications of spectator tagging with the polarized deuteron and discuss the prospects for potential fixed-target and collider experiments (JLab 12 GeV, EIC). At the EIC, proton and neutron spectators will be detected with the far-forward detectors integrated in the interaction region. While achieving deuteron beam polarization at the EIC is challenging, it is regarded as technically feasible and could be considered as a future facility upgrade.

Speaker: Christian Weiss (Jefferson Lab)

weiss23_spin23_tagging.pdf

Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy II

Convener: Thomas Jude (The University of Bonn)

50 The Polarized Target Program at GlueX

A polarized target program is being developed for GlueX in Hall D at Jefferson Lab. Consisting of a high intensity tagged photon beam with energies up to 12 GeV, a hermetic solenoidal spectrometer sensitive to charged and neutral particles and a demonstrated DAQ rate of 80 kHz, the apparatus is ideal for many polarized target experiments with longitudinal target polarization. Already approved is the Real Gamma GDH Experiment (REGGE), to measure the Gerasimov-Drell-Hearn (GDH) integrand on hydrogen and deuterium. This experiment will test the convergence of the GDH integral at high energy and the validity of the GDH sum rule to increased precision for the proton and for the neutron for the first time with a real photon beam. An expansion is being pursued which will measure the GDH sum rule on nucleons in nuclei. It is also possible to measure polarization observables from correlated nucleons within nuclei to study the relationship to the EMC effect.

Speaker: Dr Mark Dalton (Jefferson Lab)

Dalton_SPIN2023_PolTarGlueX.pdf

51 Measurement of 3He Spin Sum Rules at Low Q2

The Gerasimov-Drell-Hearn (GDH) sum rule shows a fundamental relation between real photon absorption and the anomalous magnetic moment to the spin structure of the target. The generalized form of GDH sum rule extends this relation to finite four-momentum transfer squared (Q$^2 > 0$). Jefferson Lab (JLab) experiment E97-110 was carried out with a longitudinally polarized electron beam and transversely and longitudinally polarized $^3$He targets in the experimental Hall A. The experiment measured spin-dependent cross sections for the doubly polarized electron scattering off $^3$He at small scattering angles of 6$^{\circ}$ and 9$^{\circ}$ with beam energies from 1.1 GeV to 4.4 GeV, covering the quasi-elastic region, resonances region, and beyond. The measured cross-sections are used to benchmark the calculations from impulse approximation or Faddeev formalism in the quasi-elastic region. Spin-dependent structure functions ($g_1$ and $g_2$) and their first moments are also extracted at low $Q^2$ from 0.032 to 0.23 GeV$^2$. The experimental results directly investigate the connection between the GDH sum rule at the real-photon point ($Q^2 = 0$) and its extended forms at low $Q^2$, showing a recovering trend at $Q^2 < 0.1$ GeV$^2$. This talk will present the experimental results of JLab E97-110 for the $^3$He target.

Speaker: Chao Peng (Argonne National Laboratory)

SPIN2023_SAGDH_Chao.pdf

Polarized Ion and Lepton Sources and Targets: Sources and Targets II

Convener: Marcy Stutzman (JLab)

52 Simulating Real-Time Electron Impact Ionization Within the CEBAF Photo-gun Using a General Particle Tracer (GPT) Custom Element

The operating lifetime of GaAs-based photocathodes in DC high-voltage electron photo-guns is limited by ion back-bombardment, where ions created within the photo-gun potential are accelerated toward the photocathode. This leads to an undesired reduction of the photocathode quantum efficiency (QE). At the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab, experiments were performed to test the effectiveness of biasing the anode to mitigate ion back-bombardment. The experiments demonstrated marked improvement in photocathode operating lifetime when the anode was biased. The custom element IONization And Tracking Of Residual gas (IONATOR) has been developed using the framework of General Particle Tracer (GPT) to simulate electron impact ionization in real time. While IONATOR was originally developed for simulations of the CEBAF photo-gun, it is readily extensible to other applications. The custom element uses Monte Carlo routines to calculate the ion production rate and the secondary electron kinetic energy based on user-defined gas pressures, the ionization cross section, and the secondary electron differential cross section. It then uses relativistic kinematics to track the secondary electron, the scattered electron, and the ion after ionization. The ion production rate and the secondary electron energy distribution determined by the custom element have been benchmarked against theoretical calculations. The IONATOR custom element will be described in detail and its application in GPT simulations of the biased anode experiments to improve photocathode lifetime at the CEBAF accelerator will be presented.

Speaker: Joshua Yoskowitz (ODU/JLab)

Yoskowitz_SPIN2023_Presentation_FINAL.pptx

53 High voltage DC gun using Super lattice GaAs photocathode for EIC polarized electron source

The high-intensity, polarized electron source is a critical component for the electron-ion collider, requiring a polarized electron gun with higher voltage and higher bunch charge than any existing polarized electron source. At Brookhaven National Laboratory, we have built and successfully conditioned an inverted HVDC photoemission gun up to 350 kV. In this study, we report on the performance of a GaAs photocathode in generating 70 µA average current and up to 16 nC bunch charge with a long lifetime using a circularly polarized laser at a wavelength of 780 nm. We discuss the performance of the Distributed Bragg Reflector GaAs/GaAsP Super Lattice photocathode in the DC gun, and possible reasons for the observed peak QE wavelength shift are analyzed. In addition, the impact of DBR layer and laser on the lifetime has been discussed. Further investigations are required to assess the DBR GaAs sample and enhance the performance of the polarized electron gun.

Speaker: Erdong wang (bnl)

High voltage DC gun using DBR superlattice GaAs photocathode for EIC polarized electron source_Erdong.pdf

High voltage DC gun using DBR superlattice GaAs photocathode for EIC polarized electron source_Erdong.pptx

54 First test of a polarized $^3$He$^+$ ion source

The use of polarized $^3$He ions in storage rings opens a new window to investigate nuclear forces, because the spin-dependent part of the differential cross section of the observed reactions must stem in first order from the neutron spin. Thus, nuclear polarized $^3$He$^{2+}$ beams can be regarded as an ideal substitute for polarized neutron beams. Polarized $^3$He ions were used in the 1960’s, but either the nuclear polarization and/or the usable intensity of the corresponding ion sources was rather small. Since then, several groups around the world have been working on the realization of an efficient polarized $^3$He ion source for injection into storage rings. Current concepts are based on the rapid ionization of optically-pumped polarized $^3$He gas with polarization values up to 0.8. Nevertheless, most of the different ionization processes tested so far result in large polarization losses.

A new approach at the Institute for Nuclear Physics in the Research Center Jülich promises to overcome the recent limitations with an intense (>10 μA) polarized $^3$He$^{1+}$ beam with a polarization up to P ~ 0.9 that can be used for stripping injection to feed storage rings. The method itself is similar to “optical pumping”, but instead of laser beams single radio-wave pulses are used to induce transitions within the hyperfine substates in the Zeeman region of a $^3$He$^{1+}$ beam at 4 keV. The corresponding photons are coherent and monochromatic, and the induced transitions at an energy level of $10^{-8}$ eV interfere with each other. Based on this phenomenon, the three substates of the F = 1 state can be pumped into a single substate with $m_F$ = +1 or -1. The corresponding polarization will be measured after acceleration to about 100 MeV due to the known analyzing powers of elastic scattering on protons with an existing polarimeter behind the cyclotron JULIC. In principle, this technique can be expanded to other ions, even heavy ions, and may open the door for a new generation of polarized ion sources or polarized fuel, thus increasing the energy output of future fusion reactors.

Speaker: Nicolas Faatz

Talk.3He+.pptx

Spin in Heavy Ion Collisions: Heavy Ions II

Convener: Takafumi Niida (University of Tsukuba)

55 Relativistic magnetohydrodynamics with spin

Taking into account the recent measurements of the spin-polarization of particles produced at RHIC and LHC, the self-consistent formulation of relativistic fluid mechanics for spin-polarized media subjected to a large magnetic field is of great interest to the relativistic heavy-ion collisions community [1]. To meet this need, we formulate a relativistic kinetic theory for spin-polarized particles under the influence of a magnetic field and derive equations of motion for relativistic dissipative non-resistive magnetohydrodynamics [2]. In the kinetic equation, we utilize a relaxation-time approximation for the collisional kernel and compute respective nonequilibrium corrections to the phase-space distribution function. We show how our framework naturally leads to the relativistic analogs of Einstein-de Haas and Barnett's effects. Moreover, we find respective transport coefficients and demonstrate the emergence of the link between spin and magnetic field at gradient order.

References:
[1] F. Becattini, J. Liao, M. Lisa, Lect.Notes Phys. 987 (2021) 1-14
[2] S. Bhadury, W. Florkowski, A. Jaiswal, A. Kumar, R. Ryblewski, Phys.Rev.Lett. 129 (2022) 19, 192301
[3] S. Bhadury, W. Florkowski, A. Jaiswal, A. Kumar, R. Ryblewski, to appear

Speaker: Radoslaw Ryblewski (Institute of Nuclear Physics Polish Academy of Sciences)

SPIN23 Ryblewski.pdf

56 Exact polarization of particles of any spin at global equilibrium in a relativistic fluid

The polarization of the Λ particle offers the unique opportunity to study the hydrodynamic gradients in the Quark-Gluon Plasma formed in heavy-ion collisions. However, the theoretical formula commonly used to calculate polarization is only a linear order expansion in thermal vorticity and neglects higher-order terms. Here, we present an exact calculation at all orders in (constant) thermal vorticity at global equilibrium. We resum the series and obtain the analytic form of the spin density matrix and the polarization vector for massive and massless particles of any spin or helicity. Finally, we extend our results to local equilibrium, where we evaluate their impact in heavy-ion collisions by numerically calculating polarization in a 3+1 hydrodynamic simulation for different collision energy.

Speaker: Andrea Palermo (Frankfurt UNiversity)

SPIN_Palermo.pdf

57 The most spinning baryonic matter

The study of strong interaction matter under external conditions (such as high temperatures and/or baryon densities) provides unique insights into its fundamental theory, the Quantum Chromodynamics (QCD). A nonzero angular momentum imposed on a QCD system can bring rich and intriguing phenomena, with the proton spin structure being a perfect example. A much larger QCD system with substantial angular momentum, produced by non-central heavy ion collisions, has attracted a lot of interests recently. This angular momentum induces nontrivial vortical fluid patterns in the fireball formed by the collision and eventually leads to spin polarization of final state hadrons, as shown by experimental measurements from STAR, ALICE and HADES Collaborations. A clear understanding of the angular momentum initial conditions for the fireball, such as the total amount and its rapidity distribution, is however still lacking. In this talk, we demonstrate how the baryon stopping plays a key role for the deposition of angular momentum toward mid-rapidity region. By calculating rapidity loss after multiple binary collisions for wounded nucleons, we quantify the angular momentum initial conditions for heavy ion collisions from GeV to TeV beam energies. This also allows us to explain the beam energy dependence of experimental data on spin polarization as well as to reveal a nontrivial correlation between net baryon number and initial angular momentum in the fireball. Finally we introduce the ratio of angular momentum to net baryon number as a measure for comparing “spinning-ness” and show that the most spinning baryonic matter, created in heavy ion collisions at a few GeV energies, is about an order of magnitude higher than a proton in terms of this measure.

Speaker: JINFENG LIAO (INDIANA UNIVERSITY BLOOMINGTON)

LIAO_SPIN2023.pdf

58 Discussions

Tuesday, September 26

3D Structure of the Nucleon: TMDs: TMDs III

Convener: Andrea Signori (University of Turin and INFN)

59 Longitudinal spin transfer of semi-inclusive $\Lambda$ production in deep inelastic scattering

We study the longitudinal spin transfer of $\Lambda$-hyperon production in semi-inclusive deep inelastic scattering with both current and target fragmentation mechanisms. For existing fixed-target experiments, such as JLab and COMPASS, the events from the current region and those from the target fragmentation region are not clearly separated. We find that the contribution from the target fragmentation can significantly suppress the spin transfer to the $\Lambda$ measured at existing experiments. We also perform a model estimation to quantitatively demonstrate this effect and the results are compared with COMPASS data.

Speaker: Dr Xiaoyan Zhao

spin2023.pdf

60 Hyperon polarization in SIDIS: Matching between TMD and twist-3 factorizations

We study the consistency between the TMD factorization and the collinear twist-3 factorization for the transversely polarized hyperon production in semi-inclusive deep inelastic scattering (SIDIS). The TMD approach covers the polarization in the small transverse momentum $P_{hT}$ region
of the hyperon, while the twist-3 approach covers that in the large $P_{hT}$ region. Since both frameworks provide systematic ways to the hyperon polarization, they should match consistently in the intermediate transverse momentum region. The cross section for the process
consists of five structure functions with different azimuthal depedences and we reported the complete LO result for the twist-3 cross sections arising from the twist-3 distribution function in the nucleon and the
twist-3 fragmentation function for the hyperon [1,2]. We show that, for all these contrubutions to five structure function, the result matches consistently with the TMD cross section, which indicates that the two approaches are the representation of the unique QCD effect in different kinematic region.

[1] Y. Koike, K. Takada, S. Usui, K. Yabe and S. Yoshida,
``Transverse polarization of hyperons produced in semi-inclusive deep inelastic scattering,''
Phys. Rev. D 105, no.5, 056021 (2022) [arXiv:2202.00338 [hep-ph]].

[2] R. Ikarashi, Y. Koike, K. Yabe and S. Yoshida,
``Twist-3 gluon fragmentation contribution to hyperon polarization in semi-inclusive deep inelastic scattering,''
Phys. Rev. D 105, no.9, 094027 (2022) [arXiv:2203.08431 [hep-ph]].

Speaker: Riku Ikarashi (Niigata University)

61 Measurement of transverse polarization of lambda in pp collision at STAR

Spontaneous polarization of $\Lambda/\bar{\Lambda}$ hyperon in unpolarized hadron-hadron reactions has been observed experimentally for nearly half a century and still eludes a definitive explanation. Recently significant transverse polarization of $\Lambda/\bar{\Lambda}$ was observed by the Belle experiment in unpolarized $e^{+}e^{-}$ annihilation, along the normal direction to the plane defined by the thrust axis and the $\Lambda$ momentum. A possible origin is the effect arising from polarizing fragmentation functions (PFFs), which describe the production of polarized hadrons from the fragmentation of an unpolarized parton. Presented in this talk is a status update on measurement of the polarization of $\Lambda$/$\bar{\Lambda}$ transverse to the plane defined by the jet and $\Lambda$ momentum in unpolarized $pp$ collisions collected at the STAR experiment at the center-of-mass energy of $\sqrt{s}$ = 200 GeV, with an integrated luminosity of 104 $\mathrm{pb}^{-1}$. This is the first measurement in $pp$ collisions and can provide important constraints on the PFFs. The utilized data sample is the largest collected by the STAR detector at RHIC for this collision system and energy.

Speaker: Taoya Gao (Shandong university)

SPIN2023_gty_2023.09.26_v11.pdf

62 Measurement of $\Lambda$-hyperon spin-spin correlations in $p+p$ collisions at $\sqrt{s} = 200$ and $510\,\textrm{GeV}$ by the STAR experiment

About 50 years ago, it was discovered that $\Lambda$ hyperons are produced polarized in collisions of unpolarized protons on beryllium. Despite enormous experimental and theoretical efforts, the origin of this polarization remains inconclusive to date. The $\Lambda$ polarization has also been observed in various collision systems, from $e^+e^-$ to heavy-ion collisions. A recently proposed technique for the investigation of the $\Lambda$ hyperon polarization is a measurement of $\Lambda\bar{\Lambda}$, $\Lambda\Lambda$, and $\bar{\Lambda}\bar{\Lambda}$ spin-spin correlations. This technique is expected to help understand if the polarization is generated at early stages of the collisions, e.g. from initial state parton spin correlation, or if it is a final state effect originating from hadronization.

In this talk, we present a status of the first measurement utilizing this new experimental method in $p+p$ collisions at $\sqrt{s} = 200$ and $510\,\textrm{GeV}$ by the STAR experiment. The $\Lambda$ and $\bar{\Lambda}$ candidates are reconstructed at mid-rapidity ($|y| < 1$) and in two transverse momentum ($p_\mathrm{T}$) bins which allows us to extract the $\Lambda$-hyperon spin-spin correlations for various $p_\mathrm{T}$ combinations of hyperons in $\Lambda\bar{\Lambda}$, $\Lambda\Lambda$, and $\bar{\Lambda}\bar{\Lambda}$ pairs. This measurement will provide new insight into $\Lambda$ hyperon spin polarization in $p+p$ collisions at RHIC energies.

Speaker: Jan Vanek (Brookhaven National Laboratory)

SPIN_2023_Vanek_final.pdf

63 Longitudinal and Transverse Spin Transfer of $\Lambda$ and $\overline{\Lambda}$ Hyperons in Polarized $p$+$p$ Collisions at $\sqrt{s} = 200$ GeV at STAR

The longitudinal and transverse spin transfer to $\Lambda$ and $\overline{\Lambda}$ hyperons in polarized proton-proton collisions is expected to be sensitive to the helicity and transversity distributions of strange and anti-strange quarks of the proton, as well as the corresponding polarized fragmentation functions. In this talk, we will present the improved measurements of longitudinal spin transfer to $\Lambda$ and $\overline{\Lambda}$, $D_{LL}$, and transverse spin transfer to $\Lambda$ and $\overline{\Lambda}$, $D_{TT}$, in polarized proton-proton collisions at $\sqrt{s} = 200$ GeV with the STAR experiment at RHIC. The data set includes longitudinally and transversely polarized proton-proton collision samples with an integrated luminosity of 52 pb$^{-1}$ in each cases. Both data sets have about two times larger figure of merit than prior results and cover a kinematic range of $|\eta|$ $<$ 1.2 and transverse momentum $p_T$ up to 8 GeV/$c$. We also report first measurements of the hyperon spin transfer $D_{LL}$ and $D_{TT}$ versus fractional momentum $z$ of the hyperon within a jet, which can provide more direct constraints on the polarized fragmentation functions.

Speaker: Prof. Qinghua Xu (Shandong University)

SPIN2023_spin_transfer_QXu.pdf

64 Longitudinal Spin Transfer to $\Lambda$ Hyperons with CLAS12

Using the self-analyzing decay of the $\Lambda$, the longitudinal spin transfer $D_{LL'}$ to the hyperon from a polarized electron beam scattering off an unpolarized proton target can be determined. For $\Lambda$s produced in the current fragmentation region, this quantity is proportional to the helicity dependent fragmentation function $G_1^\Lambda$ and can provide insight into the spin structure of the $\Lambda$. Currently, limited experimental data on $D_{LL'}$ cannot discriminate between different models of $\Lambda$ spin structure. This contribution reports on the measurement of the longitudinal spin transfer using data taken by the CLAS12 spectrometer at Jefferson Lab with a 10.6 GeV polarized electron beam. We also report on status of the ongoing analysis of spin transfer and back-to-back hadron correlations with target fragmentation $\Lambda$s.

Speaker: Matthew McEneaney (Duke University)

McEneaney_SPIN2023_9_26_23.pdf

Application of Nuclear Polarization Techniques to Other Fields: Applications I

65 Better at the Bottom: 21st Century millitesla MRI

A promising approach to portable MRI is operation at ultra-low magnetic field where cost-effective electromagnets become practical. MRI in the ultra-low field (ULF) regime —when the magnetic field used for signal detection is below 10 mT—is inherently challenging mainly due to intrinsically low Boltzmann polarization. We will discuss signal acquisition approaches and hardware methods to improve attainable SNR in the Johnson-noise-dominated Larmor frequency of 276 kHz (6.5 mT). We will also discuss our work to reduce noise and increase attainable information per unit time using compute-based approaches that leverage low-cost GPU. These include magnetic resonance fingerprinting (MRF) to enable multiple quantitative contrasts at ULF, and the use of our neural network deep learning approach, AUTOMAP, to reconstruct highly-undersampled low SNR imaging data. In addition, we will discuss several classes of NMR and MRI experiments enabled by operation at low magnetic field, which can outperform what can be done with high-field instruments, including new clinical use cases.

Speaker: Matt Rosen (MGH/Martinos Center for Biomedical Imaging)

66 Practical metabolic imaging with hyperpolarized nuclei

Creating and maintaining hyperpolarized states is difficult. Unsurprisingly, many of the same limitations are also present when considering biological and medical applications. T1, T2, diffusion or transport to the catalytic site of interest and relaxation processes while bound can all affect our ability to extract useful information from the hyperpolarized sample in vivo. Even when these effects do not preclude the imaging agents that are accessible to hyperpolarization techniques, they may confound straightforward interpretation in terms of metabolic changes of diagnostic value.
For example, in the case of the most widely-used hyperpolarized agent, pyruvate, observation of accelerated intracellular reduction to lactate is observed in many cancer types, and can be used to identify tumors or assess their aggressiveness. However, as is the case with 18F-FDG PET and other molecular imaging methods, quantitative and even qualitative interpretation is very hard to do-- local changes in perfusion, vessel leakiness, vascularity, transport across cell membranes, inflammatory infiltration, intra- or extracellular pH, and local or systemic lactate concentration can all affect the apparent reduction rate, confounding and potentially masking clinically relevant alterations.
In this talk I will discuss our efforts to disentangle these effects using additional measurements and a rational agent selection approach. The process consists of first assessing protein expression and metabolite concentration differences that indicate the hyperpolarization-accessible agent with the best ability to distinguish between health and disease states of interest. We then test the agent in isolated organ or patient-derived xenograft (PDX) models to confirm the expected sensitivity. Next, we simulate agent metabolism using a multi-compartment model and use a Bayesian analysis approach to both support fusion with other data sources, and to evaluate / minimize remaining diagnostic uncertainty. Finally, we will apply this optimized and hopefully specific imaging method to a human study to verify clinical utility. I will detail this approach in the context of our current goal of subtyping Human Hepatocellular Carcinoma to inform precision treatment selection at Penn.

Speaker: Dr Stephen Kadlecek (stephen.kadlecek@pennmedicine.upenn.edu)

67 Next-generation Enabling Hyperpolarized Clinical Technologies

INTRODUCTION: The vast majority of emerging hyperpolarized MRI contrast agents employ heteronuclei (e.g. 13C or 129Xe) for transient storage of hyperpolarization and detection due to much longer lifetimes of the HP state and the lack of background signal. However, clinical MRI scanners are often poorly suited for excitation and detection of heteronuclei as they typically lack the corresponding RF hardware and software. While multi-nuclear detection capability exists on clinical research MRI scanners, to date their number (<0.5%) is inconsequential for the purpose of achieving widespread implementation of HP MRI.
METHODS/RESULTS: We report on our progress in developing three distinct approaches to enable detection of HP contrast media on clinical MRI scanners equipped with proton-only hardware and software. The first strategy employs proton sensing of 13C-hyperpolarized metabolites in vivo (most notably hyperpolarized pyruvate and its downstream metabolites). The second approach relies on the use of ultrafast electronics to “translate” excitation pulses at proton frequency to a given heteronuclear frequency. In this approach, a transmit-receive RF coil is required to transmit excitation pulses and detect the heteronuclear signal. The detected signal is then “translated” back to the proton frequency of the MRI scanner, and can be “fed” to the MRI scanner for image visualization or processed off-line. Radiofrequency Amplification by Stimulated Emission of Radiation (RASER) is the third most promising approach. RASER signals are created via stimulated emission by “negatively” hyperpolarized spins without external radio-frequency excitation pulses (and thus not requiring the RF excitation coil and the pulse-sequence-synchronization) and without any background signal. The recently demonstrated feasibility of RASER MRI, 13C RASER, and the tracking of chemical transformation, and achieving ultra-high Q of 1 million of detecting NMR RF chain will be discussed. Together, these advances suggest the feasibility of 13C and 129Xe RASER imaging in vivo, using heteronuclear purpose-built high Q detection electronics for clinical MRI scanners.

Speaker: Eduard Chekmenev (Wayne State University)

Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy III

Convener: Chao Peng (Argonne National Laboratory)

68 Experiments with ultracold neutrons at PSI

The ultracold neutron (UCN) source at the Paul Scherrer Institut is being successfully operated since 2011 and has provided UCN for example to the nEDM experiment, which has placed the tightest constraints to date on the neutron's electric dipole moment in 2020. Currently the successor experiment n2EDM is being commissioned at the same position. At the second beam port, the neutron lifetime experiment $\tau$SPECT, developed at Johannes Gutenberg University Mainz, is currently being set up for data taking. $\tau$SPECT is the first neutron lifetime experimen using spin-flip loading and 3-dimensional magnetic storage of neutrons.

In this talk, the status of both experiments and first results from commissioning with neutrons will be presented.

Speaker: Dieter Ries (Paul Scherrer Institut)

DRiesUCN_SPIN23.pdf

69 Recent baryon spectroscopy results from the CBELSA/TAPS experiment

Investigating the baryon excitation spectrum is essential for understanding the internal dynamics of baryons and quantum chromodynamics (QCD) in the non-perturbative regime. Experimentally, the baryon spectrum can be probed with a real photon beam in photoproduction reactions. Partial wave analyses are performed to extract the baryon resonance parameters from the experimental data. For an unambiguous solution, the measurement of several single and double polarization observables is crucial.
The CBELSA/TAPS experiment at the accelerator facility ELSA in Bonn has a dedicated program towards measuring a large set of polarization observables in many different photoproduction reactions using polarized photon beams and polarized targets. The detector setup is excellent at measuring neutral mesons in the final states, using electromagnetic calorimeters that cover almost the full solid angular range. This talk will give an overview about recent results in non-strange baryon spectroscopy at ELSA.

Speaker: Annika Thiel (HISKP Bonn)

Talk_AThiel.pdf

70 Results on proton GPDs from lattice QCD

Generalized parton distributions (GPDs) are important quantities that characterize the 3-D structure of hadrons, and complement the information extracted from TMDs. They provide information about the partons’ momentum distribution and also on their distribution in position space. Most of the information from lattice QCD is on the Mellin moments of GPDs, namely form factors and their generalizations. Recent developments in calculations of matrix elements of boosted hadrons coupled with non-local operators opened a new direction for extracting the x dependence of GPDs.

In this talk, we present the evolution of lattice results on proton GPDs highlighting the advances in the field and presenting a new promising approach to extract GPDs for a dense range of their parameters. This method utilizes a Lorentz invariant parametrization that leads to more effective calculations of GPDs applicable for any kinematic frame, with freedom in the transferred momentum distribution. All results have been extracted using one ensemble of 𝑁𝑓=2+1+1 twisted mass fermions with a clover improvement. The value of the light-quark masses leads to a pion mass of about 260 MeV.

Speaker: Martha Constantinou (Temple University)

SPIN_2023_Constantinou.pdf

Nucleon Helicity Structure: Helicity III

Convener: Andrey Tarasov (North Carolina State University)

71 Extracting parton distribution functions from lattice quantum chromodynamics

Parton distribution functions (PDFs) capture the one-dimensional longitudinal momentum structure of hadrons and relate the properties of hadrons to their constituent quarks and gluons. Helicity PDFs, in particular, encode information directly relevant to the origin of hadron spin. Our knowledge of the PDFs of the nucleon has been significantly improved by the wealth of data from the Large Hadron Collider, but many aspects of the partonic structure of hadrons are still unclear. I review recent progress in the world-wide efforts to determine PDFs from lattice quantum chromodynamic (QCD), the numerical solution of QCD on a Euclidean spacetime lattice, and outline some of the challenges involved in these first-principles calculations.

Speaker: Chris Monahan (William & Mary)

monahan_spin2023.pdf

72 The gluon helicity from Lattice QCD

I describe recent progress by the HadStruc Collaboration at extracting the helicity distribution from Lattice QCD calculations using the pseudo-PDF framework. I begin by briefly outlining the pseudo-PDF framework, before proceeding to its implementation for our study of the gluon PDF. I describe the variety of methods employed to overcome the poor signal-to-noise ratios inherent in such calculation: the distillation framework, gradient flow, and the use of the variational method. I conclude with a discussion of the potential of first-principles lattice calculation and experimental data together to provide further constrains on the gluon helicity content of the nucleon than can be accomplished by computation or experiment alone.

Speaker: David Richards (Jefferson Lab)

DIS09262023.pdf

73 Nucleon structure from pseudo-distributions

Pseudo-distributions, which regularized co-linear divergences using space-like separations in quark bilinear operators, are accessible from lattice QCD calculations in Euclidean space. In the recent years, parton distribution functions have been computed in lattice QCD using this approach. In this talk I present recent results by the HadStruc collaboration utilizing the pseudo-distribution approach.

Speaker: Kostas Orginos (William and Mary / JLab)

spin_2023.pdf

Polarized Ion and Lepton Sources and Targets: Sources and Targets III

Convener: Joe Grames (JLab)

74 A universal method to polarize atoms, molecules, and their ions for accelerators, nuclear fusion, or medical applications

Our study of atomic beams passing through a static magnetic field, whose direction reverses along the axis of motion, gave rise to a new, versatile polarization method. For instance, a sinusoidal magnetic field entails a radial component, which is proportional to the gradient in the longitudinal direction. Such a field can be generated by two opposing solenoid coils. As a particle beam travels through the coils, it experiences the static field as an electromagnetic wave in its rest frame. The longitudinal component creates an energy splitting between the atomic hyperfine states and the radial component induces transitions between them. The hyperfine transitions can be described by the absorption of an odd multiple of the corresponding photon energy, so that the total photon energy is equal to the energy splitting between the states. The energy of the photons depends on the relative motion between the particle beam and the magnetic field (for a given wavelength of the sinusoidal field), and the number of the photons rises with increasing magnetic field strength. Therefore, oscillating transition rates are observed while ramping the magnetic field of the apparatus. As a result, it is feasible to achieve a high degree of polarization by adjusting the magnetic field strength. The produced polarization is higher for particles with simple hyperfine structures, e.g., H, D, $^{3}$He$^{+}$, etc. These species are required for the investigation of nuclear fusion with polarized fuel or polarized ion sources for accelerators. First measurements with metastable hydrogen beams will be presented. Furthermore, the applicability of this method to molecular samples (for medical applications) needs to be examined.

Speaker: Chrysovalantis Kannis (GSI Helmholtzzentrum für Schwerionenforschung, Forschungszentrum Jülich)

spin2023_kannis_public.pptx

75 Polarized ion sources at BNL

The Optically Pumped Polarized Ion Source (OPPIS) provided polarized H$^-$ to the injector chain of the RHIC. The scheme used in the OPPIS is as follows: An atomic hydrogen beam produced by an external source is injected into a He-gas ionizer cell inside a high magnetic field solenoid to produce a proton beam. This proton beam then passes through an optically pumped Rb vapor cell and picks up a polarized electron. The polarization is transferred to the proton through a spin-exchange transition. Finally, the polarized H atom passes through a sodium cell and picks up an extra electron and is extracted at 35 keV. The use of a high-brightness primary beam and large cross-sections of charge-exchange cross-sections resulted in the production of a high-intensity H$^-$ ion beam of 85% polarization. High beam brightness and polarization resulted in 75% polarization at 23 GeV out of the AGS and 60-65% beam polarization at 100-250 GeV colliding beams in RHIC.
We are also developing a high-intensity (2e$^{11}$ ions per pulse) 3He$^{++}$ polarized ion source for the future Electron Ion Collider (EIC). This source will use a new technique which is based on the polarization of accumulated ultra-pure 3He gas in a high magnetic field by metastability-exchange optical pumping. Polarized gas will be ionized by the electron beam of the existing Electron Beam Ion Source (EBIS). An infrared laser system for pumping and measurement in the high field of EBIS has been developed. In the test setup, polarization of 80-85% has been achieved for ultra-pure 3He gas in the "Open" cell configuration with refilling valve tube inlet and isolation valve closed. The development of the spin-rotator and 3He-4He absolute nuclear polarimeter at 6 MeV 3He$^{++}$ beam energy is also presented.

Speaker: Deepak Raparia (BNL)

BNL polarized ion source_raparia_spin23.pptx

76 Operation of a CLAS12 Longitudinally Polarized Solid Nuclear Target in RGC

A suite of experiments measuring target-spin observables in electron-nucleon scattering (dubbed Run Group C) was recently executed in Jefferson Lab. These experiments involved the scattering of an 11 GeV electron beam from longitudinally polarized nucleon targets located within the CLAS12 spectrometer in Hall B. The dynamically polarized target used in these experiments was designed and constructed exclusively for operation inside the CLAS12 and further optimized for the requirements of Run Group C. We will report on the operational experience with the target, the benchmarks achieved using various polarizable and unpolarized materials as well as the complete target setup, and the comprehensive target polarization analysis.

This work was funded in part by the National Science Foundation under contract PHY-1002462 and the US Department of Energy under contract DE-FG02-96ER40960 and contract DE-AC05-06OR23177

Speaker: Pushpa Pandey (Old Dominion University)

SPIN2023_Pushpa_Pandey.pptx

Spin in Heavy Ion Collisions: Heavy Ions III

Convener: JINFENG LIAO (INDIANA UNIVERSITY BLOOMINGTON)

77 Vector meson spin alignments in high energy reactions (invited abstract)

The observation of global vector meson alignment in heavy ion collisions by the STAR collaboration at RHIC has attracted further attention to polarization effects in this filed. In this talk, I would like to make a brief overview of vector meson spin alignment in different high energy reactions and/or different hadronization mechanisms. I will briefly summarize the progresses of different theoretical approaches and their comparisons with available data and present a short outlook for future studies.

Speaker: Zuo-tang Liang (Shandong University)

Spin2023.pdf

78 Vector meson polarization measurements in pp and Pb--Pb collisions with ALICE at the LHC

Polarization measurements represent an important tool for understanding the particle production mechanisms occurring in proton proton collisions. In particular, for quarkonium states, the very small polarization measured at the LHC represents a serious and a long-lasting challenge for theoretical models. When considering heavy-ion collisions, particle polarization could also be used to investigate the characteristics of the hot and dense medium (quark-gluon plasma) created at LHC energies. Recently, it has been shown that light vector mesons produced in Pb–Pb collisions are polarized, an effect likely due to the presence of a large angular momentum of the strongly interacting system produced in non-central heavy-ion collisions, because of spin-orbital coupling. It has also been conjectured that quarkonium states could be polarized by the strong magnetic field generated in the early phase of the evolution of the system.
\par This talk will present the first measurement of J/$\psi$ polarization in Pb--Pb collisions at forward rapidity and the recent measurements of spin alignment for $K^{\star}$(892) and $\phi$(1020) mesons at midrapidity for different reference frames (event plane, production plane, random plane) in Pb--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV, obtained with the ALICE detector. The results will be discussed and compared with previous measurements from the pp collision system.

Speaker: Xiaozhi Bai (University of Science and Technology of China)

spin_xbai_v4.pdf

79 Tensor polarization and spectral properties of vector meson in QCD medium

Under the framework of thermal field theory, we calculate the tensor polarization and the resulted spin alignment of a generic vector meson in local equilibrium up to the first order in the hydrodynamic gradients.
At the zeroth order, the spin alignment of the vector meson emerges mainly due to the degeneracy breaking between the transverse and longitudinal spectral functions.
At the first order, the tensor polarization can be induced by the hydrodynamic gradients allowed by symmetry, including a shear-induced tensor polarization (SITP) contribution. The corresponding coefficients are calculated using linear response theory up to the order of one loop, and turns out sensitive to the in-medium spectral properties of vector bosons, e.g., the width and in-medium mass-shift. Moreover, within the framework of relativistic hydrodynamics, we find that the SITP together with other contributions could generate substantial spin alignment in heavy-ion collisions, which is within the relevant range of experimental measurements. These results suggest that the spin alignment could be utilized as a new probe revealing the in-medium spectral properties and the microscopic interactions of the medium constituents. The newly discovered SITP effect is universal in both relativistic and non-relativistic cases, and may therefore also be observed in the low energy systems, such as plasma at relatively low energy and cold atomic gases.

Speaker: Feng Li (School of physics, Lanzhou University)

80 Measurement of $J/\psi$ polarization and spin alignment in Ru+Ru and Zr+Zr collisions at $\sqrt{s_{_{\rm NN}}} = 200$ GeV at STAR

The large scale set by the charm mass means the heavy quark pairs are produced early in heavy-ion collisions and experience the full evolution of the quark-gluon plasma (QGP) created in these collisions. Because of this, $J/\psi$ serves as one of the important probes to study the properties of the QGP. In Ru+Ru and Zr+Zr collisions at $\sqrt{s_{_{\rm NN}}} = 200$ GeV recorded by the STAR experiment, it has been observed that the $J/\psi$ yield is strongly suppressed and its elliptic flow is consistent with zero indicating the $J/\psi$'s strong coupling with the medium and its potentially small regeneration contribution, respectively. Besides those observable, the $J/\psi$ polarization can shed new light on the QGP properties and the $J/\psi$ production mechanism in heavy-ion collisions. For example, it has been hypothesized that the $J/\psi$ polarization can be observed due to the spin-orbit coupling between $J/\psi$ and the QGP's large angular momentum in non-central heavy-ion collisions. The early production of $J/\psi$ also makes its polarization potentially sensitive to the strong magnetic field at the early stage.
In this talk, we will present the first measurement of $J/\psi$ polarization in heavy-ion collisions at RHIC. The study is carried out by reconstructing the $J/\psi$ through its di-electron decay channel in the mid-rapidity ($|y| < 1$) and the $J/\psi$ transverse momentum range of $0.2 < p_T < 10$ GeV/$c$. The $J/\psi$ polarization parameters are measured in the Helicity frame, Collins-Soper frame and with respect to the event plane. We conclude by presenting the physics implications of this measurement.

Speaker: Dandan Shen

spin_Dandan_polarization_and_spin_alignment.pdf

Spin physics in Nuclear Reactions and Nuclei: Nuclei I

Convener: Elena Long (University of New Hampshire)

81 Defining the Benchmarks for the Extraction of Information from Polarized Deep Exclusive Scattering

I will describe a framework defining benchmarks for the analysis of polarized exclusive scattering cross sections using physics constraints including lattice QCD, built into machine learning (ML) algorithms. Both physics driven and ML based benchmarks are applied to a wide range of deeply virtual exclusive processes through explainable ML techniques with controllable uncertainties. The observables, namely the Compton Form Factors (CFFs) which are convolutions of Generalized Parton Distributions (GPDs), are extracted using a quantification technique, the random targets method, that allows us to address the separation of aleatoric and epistemic uncertainties in exclusive scattering analyses.

Speaker: Simonetta Liuti (Argonne National Laboratory)

liuti_SPIN_23.pdf

liuti_SPIN_23.pptx

82 DVCS on Polarized Nucleons with the CLAS12 experiment at Jefferson Lab

Deeply Virtual Compton Scattering is the most direct channel to access Generalized Partons Distributions (GPD) and understand more about the 3D structure of the nucleon, the origin of its spin and the forces at play within it. Complete extraction of GPDs require the use of polarized electron beams and polarized nucleon targets in DVCS measurements.

In 2009, the CLAS collaboration measured DVCS on longitudinally polarized protons with a 6 GeV electron beam. This year, a new JLab experiment that just ran at 10.6 GeV will allow to extend the previous results by measuring DVCS off longitudinally polarized protons and neutrons in hydrogen and deuterium targets with the CLAS12 detector. In particular, target-spin and double-spin asymmetries will be measured for the first time for neutron DVCS. These results, alongside with beam-spin asymmetry measurements of nDVCS, will allow to extract neutron Compton Form Factors and access the H and E GPDs for the neutron. Combining results on the proton and the neutron will also allow for flavor decomposition of GPDs. Preliminary DVCS measurements on polarized protons in hydrogen have been conducted and will be presented, alongside with the experimental program on protons and neutrons.

Speaker: Noémie Pilleux (IJCLab, Université Paris Saclay)

DVCS_polarized_nucleons_CLAS12-Pilleux.pdf

83 Polarization Observables with a Photon Probe

The polarized target program in Hall D at Jefferson Lab, which began to measure the Gerasimov-Drell-Hearn (GDH) integrand on hydrogen and deuterium, presents a unique opportunity for nuclear physics with a photon probe. The polarized target apparatus will allow polarization observables to be measured with a photon beam on polarized nuclei such as Li-7, C-13, N-15, O-17, and F-19 with photon energies up to 12 GeV. This data would allow the measurement of the GDH integrand of a nucleon in the nucleus which may allow the extraction of information on nuclear medium modifications [Bass20, Bass22]. As an inclusive measurement this would have a statistical advantage over many methods of probing nuclear modifications. It is reported that short range correlations will depolarize the paired nucleons [Thomas18] so that a change of the structure function of a high momentum, far off-mass-shell nucleon in a correlated pair, can only lead to very small EMC effect on the nuclear spin structure function. This can be tested by studying target spin asymmetries as a function of the relative momentum between two correlated nucleons, particularly in the region above the Fermi momentum.

[Bass20] https://doi.org/10.5506/APhysPolB.52.43
[Bass22] https://doi.org/10.48550/arXiv.2212.04795
[Thomas18] https://doi.org/10.1142/S0218301318400013 International Journal of Modern Physics EVol. 27, No. 12, 1840001 (2018)

Speaker: Dr Mark Dalton (Jefferson Lab)

Dalton_SPIN2023_Nuclear.pdf

Joint GPD/Future: Joint GPD/Future I

Convener: Jan Matoušek (Charles University (Prague, CZ))

84 Threshold charmonium photoproduction with GlueX

We report the total and differential cross sections for $J/\psi$ photoproduction with the large acceptance GlueX spectrometer at the 12 GeV JLab accelerator over the full near-threshold kinematic region. The GlueX experiment uses tagged linearly-polarized photon beam from coherent Bremsstrahlung off thin diamond. The charmonium photoproduction near threshold, under certain assumptions including gluon exchange and factorization, can be used to study important aspects of the gluon structure of the proton, such as the gluon GPD, the gravitational form factors, the mass radius of the proton, and the anomalous contribution to the proton mass. In the measured cross sections we find evidence for possible contributions beyond gluon exchange. The results are compared to a wide range of theoretical predictions including GPD calculations and models with open-charm intermediate states. Photoproduction near threshold of charmonium states with opposite-to-photon parity offer another opportunity, complementary to the $J/\psi$, to understand the reaction mechanism of the charmonium photoproduction. While we see some evidence for such states, comprehensive studies of such higher-mass charmonia can be done only with the proposed JLab energy upgrade. An electron beam energy of up to 22 GeV increases significantly the photon flux and polarization in the corresponding threshold regions allowing precise cross section, as well as polarization measurements there.

Speaker: Lubomir Pentchev (Jefferson Lab)

LPentchev_Jpsi_SPIN23.pdf

85 Deep Exclusive Meson Production as a probe to the puzzle of $\Lambda$ hyperon polarization

In the 1970s, the unexpected discovery of transverse $\Lambda$ polarization in unpolarized proton-Beryllium collisions marked the beginning of investigating spin phenomena in high-energy physics. Over the past 50 years, similar transverse $\Lambda$ polarization has been observed in various collision systems, including hadron-hadron collisions, lepton-hadron deep inelastic scattering, and electron-positron annihilation. Despite numerous promising models and theoretical frameworks, the underlying mechanism behind this polarization phenomenon remains inconclusive to this day. However, in both longitudinally and transversely polarized lepton-hadron and hadron-hadron collisions, it has been found that the $\Lambda$ hyperon does not acquire polarization relative to the initial parton spin polarization direction. Understanding how the $\Lambda$ hyperon does or does not obtain its spin has become one of the most crucial questions in understanding hadron spin structures. In this talk, I will present a new experimental proposal that employs an exclusive process called Deep Exclusive Meson Production (DEMP) to explicitly test the mechanism of $\Lambda$ polarization. The results of this experiment are expected to shed light on the dominant mechanism by which the $\Lambda$ acquires its spin, thereby resolving many of the ambiguities encountered previously. Finally, I will discuss the experimental opportunities and challenges that lie ahead at the Electron-Ion Collider.

Speaker: Zhoudunming Tu (BNL)

Slides-Tu.pdf

86 Opportunities with the polarized internal target at EIC

A fixed target experiment, HERACLES, similar to HERMES but with 500 times higher figure-of-merit, at EIC will allow a big advance in hadron physics. The internal target with the polarized hadron beam has an important physics program. The high intensity photon beam will allow to study photo-production of the excited states and recently discovered XYZ states. We will present the analysis of experiment luminosity and ideas on an initial physics program.

Speaker: Dr Bogdan Wojtsekhowski (Jefferson Lab)

Heracles-BW.pdf

10:35 AM Coffee Break

3D Structure of the Nucleon: TMDs: TMDs IV

Convener: Leonard Gamberg (Penn State Berks)

87 Recent results on TMD extractions from the MAP Collaboration

In this talk, we present the latest results of the MAP collaboration (github.com/MapCollaboration) about the extraction of Transverse-Momentum-dependent Distributions (TMDs). We discuss in particular the extraction of unpolarized quark TMD Parton Distribution Functions (TMD PDFs), unpolarized TMD Fragmentation Functions (TMD FFs), and longitudinally polarized TMD PDFs.

Speaker: Alessandro Bacchetta (University of Pavia and INFN Pavia)

Duke_SPIN_2023.pdf

88 Tomography of pions and protons from transverse momentum dependent distributions

We perform the first simultaneous extraction of parton collinear and transverse degrees of freedom from low-energy $pA$ and $\pi A$ fixed-target Drell-Yan data in order to compare the transverse momentum dependent (TMD) parton distribution functions (PDFs) of the pion and proton. Specifically, we extract both pion PDFs and TMD PDFs simultaneously, and at the same time, we extract proton TMD PDFs in this analysis. We demonstrate that the average transverse separation of the quark field encoded in TMDs of the pion is less than that in the proton by more than $5 \sigma$. The behavior of this average transverse separation of the quark field is that it decreases as its longitudinal momentum fraction, $x$ decreases. In studying the nuclear modification of TMDs, we find clear evidence for a transverse EMC effect. We comment on possible explanations for these intriguing behaviors, which call for a deeper examination of tomography in a variety of strongly interacting quark-gluon systems.

Speaker: Patrick Barry (Jefferson Lab)

Barry_SPIN.pdf

89 Proton 3D reconstruction with time-reversal odd TMD gluon densities

We present exploratory studies of the 3D gluon content of the proton, as a result of analyses on leading-twist transverse-momentum-dependent (TMD) gluon distribution functions, calculated in a spectator model for the parent proton. Our formalism embodies a fit-based parameterization for the spectator-mass density, suited to describe both the small and the moderate-x regime. Particular attention is paid to the 𝑇-odd gluon TMDs, which represent a key ingredient in the description of relevant spin-asymmetries emerging when the nucleon is polarized, as the gluon Sivers effect. All these analyses are helpful to shed light on the gluon dynamics inside nucleons and nuclei, which is one of the primary goals of new-generation colliders, as the Electron-Ion Collider, the High-Luminosity LHC its fixed-target program.

Speaker: Francesco Giovanni Celiberto (UAH Madrid)

talk_SPIN_2023_Celiberto_T-odd_gluon_TMDs.pdf

90 Modeling and simulation of quark spin effects in electron-positron annihilation to hadrons

We present a recursive quantum mechanical model for the fragmentation of a string stretched between a quark and an antiquark with entangled spin states. The quarks are assumed to be produced in the $𝑒^+𝑒^−$ annihilation process via the exchange of a virtual photon and the correlations between their spin states are described by a joint spin density matrix. The string fragmentation process is formulated at the amplitude level by using the splitting matrices of the recent string+${}^3𝑃_0$ model of polarized quark fragmentation with pseudoscalar and vector meson emissions, and accounts for the systematic propagation of the spin correlations in the fragmentation chain. The model is formulated as a recursive recipe suitable for a Monte Carlo implementation and it is implemented in the Pythia 8.3 event generator allowing for the first time to simulate the $𝑒^+𝑒^−$ annihilation process to hadrons with quark spin effects. After validating the generator, we carry simulations of $e^+e^-$ annihilations and obtain the results for the Collins asymmetries for back-to-back hadrons. The comparisons of the simulation results with data from BELLE, BABAR and BESIII experiments are presented and discussed.

Speaker: Albi Kerbizi (INFN Trieste)

Kerbizi_SPIN2023.pdf

Application of Nuclear Polarization Techniques to Other Fields: Application II

91 Application of Hyperpolarization for Low-Field NMR and Nuclear Spin Optical Rotation Measurements

Nuclear spin hyperpolarization uncouples the magnitude of spin magnetization from that of an externally applied magnetic field, making NMR and magneto-optical measurements possible over a wide range of field strengths. In this presentation, we use dissolution dynamic nuclear polarization (D-DNP) and para-hydrogen induced polarization (PHIP) for measurements of NMR and nuclear spin optical rotation (NSOR). Low-field, milli-Tesla NMR accesses a different regime of molecular dynamics than the Tesla range magnetic fields frequently used for NMR in Chemistry and Biochemistry. We illustrate the application of cross- and R₂ relaxation measurements for the study of molecular interactions of small molecules and small-molecule ligands with biological macromolecules. Thereby, signals of hyperpolarized ¹H and ¹⁹F spins are detected inductively, in single scans, at Larmor frequencies between ~10-100 kHz. At the same magnetic field, optical signals from a specific location within a molecule can be addressed through NSOR, by radio frequency pulses acting on nuclear spins. The NSOR effect holds promise for creating a combined optical/NMR spectroscopy with site selectivity in a molecule. NSOR may further be used for a readout of spin coherence with spatial localization by a focused optical beam, as may be required for future quantum information science applications of NMR. NSOR signals from single quantum coherences are observable in dilute solution with ¹H and ¹⁹F spin hyperpolarization generated by D-DNP. We measure NSOR constants of trifluoroethanol and dimethyl sulfoxide at 405 nm, where the latter molecule at the otherwise required high concentration would exhibit prohibitive optical absorption.

Speaker: Christian Hilty

92 Towards Applications for Next-Generation Hyperpolarization Techniques and “Unusual” Isotopes and Spin States: Neutron-Optics-Based TRIV searches, MOF-created HP Orthohydrogen, and HP Imaging with Point-of-Care MRI Scanners

Nuclear spin hyperpolarization has long been exploited to enable a host of applications, from fundamental physics experiments to enhanced NMR / MRI. In order to take such efforts in new directions, our lab’s collaborative work is investigating the use of two hyperpolarization methods – Spin-Exchange Optical Pumping (SEOP) and SABRE (Signal Amplification By Reversible Exchange, a parahydrogen-based technique). First, we have been investigating the use of SEOP and SABRE to hyperpolarize 131Xe and 117Sn, respectively. These isotopes have gained recent interest as potential targets for sensitive searches for time-reversal violation in neutron-nucleus interactions beyond the Standard Model. Unlike 129Xe (with spin I=1/2, and readily polarized to near-unity values via SEOP), 131Xe is quadrupolar (I=3/2), and the resulting short T1 relaxation times make it very difficult to hyperpolarize 131Xe in bulk. With the help of next-generation spectrally-narrowed lasers and low-field in-situ NMR, we have been able to generate HP 131Xe with P up to 7.6%, corresponding to a ~100-fold improvement in P*N over previous efforts—work that has also helped to enable the first measurement of neutron-Xe pseudomagnetic precession. We have also performed the first studies of SABRE-hyperpolarized 117Sn (I=1/2), with implications for NOPTREX (neutron optics parity- and time-reversal experiments).

Next, we have been investigating the preparation and characterization of metal-organic frameworks (MOFs) as supports for SABRE under heterogeneous conditions (“HET-SABRE”). In the course of these efforts, we found a novel manifestation of a previously observed effect: the creation of hyperpolarized orthohydrogen (o-H2, the triplet spin isomer). Here, our observations were unexpected not only because the HP o-H2 signals were so large – with 1H enhancements up to ~500-fold -- but that they were also anti-phase in nature. Such an observation is seemingly paradoxical, because the resonances from the two transitions from the T0 state should ostensibly cancel. We found that this anomalous effect is attained only when using an intact MOF catalyst and is qualitatively independent of substrate nature. This observation is analogous to the “partial negative line” (PNL) effect recently explained in the context of Parahydrogen Induced Polarization (PHIP) by Ivanov and co-workers. The two-spin order of the o-H2 resonance is manifested by a two-fold higher Rabi frequency, and the lifetime of the antiphase HP o-H2 signal is extended by several-fold. Potential implications of this effect will be discussed.

Finally, the increasingly strong magnets used in most clinical scanners are expensive, bulky, and immobile, and scans can be time-consuming and confining. Low-field (LF) MRI can potentially obviate such limitations; however, sensitivity and contrast can be limited. Thus, the increased sensitivity and contrast provided by HP agents can be highly synergistic with low-field MRI. Our collaboration is working to integrate multiple HP approaches with low-field MRI platforms--including a 64 mT portable "point-of-care" scanner (Hyperfine). We are investigating the potential for adapting this type of clinical scanner for use with HP substances. We have recently demonstrated imaging of HP pyrazine and nicotinamide (via SABRE), with small-volume imaging performed in a head-coil with a resolution of 1x1x3.5 mm3 in <15 s. We are currently working to integrate this platform with a ~30-fold scaled-up continuous-flow SABRE reactor. A longer-term goal is to enable imaging of PHIP-hyperpolarized propane gas with partial spin-lock-induced crossing (SLIC)-modified sequences.

Speaker: Boyd Goodson (Southern Illinois University Carbondale)

93 Polarization REsearch for Fusion Experiments and Reactors - The PREFER collaboration: Goals and present status

The PREFER (Polarization REsearch for Fusion Experiments and Reactors) collaboration was born to address the challenge of achieving nuclear fusion with polarized fuel, for improved fusion-reactor efficiency, by bringing together techniques and know-how from different fields. Efforts are focused on a variety of tasks and objectives, which are under the responsibility of different institutes. Starting from open questions in fusion reaction physics, such as the study of d-d spin-dependent cross sections, to measurements of nuclear polarization conservation in laser-induced fusion plasmas, there is still undiscovered terroir to explore. The collaboration aims to produce nuclear polarized molecules, recombined from polarized atomic beams, which are then trapped and transported to the point of use; or alternatively a newly discovered resonance (“Sona”) transition technique promises sufficient intensity for the feeding of fusion reactors directly. Other options of production are investigated, like the production of spin-polarized molecules from the IR-laser-excitation of molecular beams, and also from molecular photodissociation. The presentation provides the status of these investigations in the European community.

Speaker: Giuseppe Ciullo (Dipartimento di Fisica e SdT - Università degli studi di Ferrara AND Istituto Nazionale di Fisica Nucleare - sezione di Ferrara)

2023_09_26_SPIN2023_Ciullo_LAST.pptx

Fundamental Symmetries and Spin Physics Beyond the Standard Model: Fundamental Symmetries III

94 Baryon number-violating amplitudes on a lattice

Neutron-antineutron oscillations and proton decay are long-sought manifestations particle unification models. At least one of these phenomena is expected to exist due to the observed baryon asymmetry of the Universe. Constraints on unification and beyond-standard models from existing and newly proposed experiments depend heavily on nucleon and nuclear matrix elements of quark-level BNV operators. These amplitudes are determined by nonperturbative QCD dynamics and must be computed numerically to avoid nucleon model uncertainties. Within the past few years, these amplitudes have been computed on a lattice with tight control over most sources of systematic effects. I will present results and discuss implications of these calculations for neutron-antineutron oscillations and proton decays.

Speaker: Sergey Syritsyn (Stonybrook)

2023spin-syritsyn-bnvlat.pdf

11:20 AM Discussion

95 An Update To The First Search for Neutron to Mirror-Neutron Oscillations Using Neutron Electric Dipole Moment Measurements

Baryogenesis requires baryon number violation. Certain extensions to the Standard Model have proposed the existence of an exact, but parity-conjugated, copy of the ordinary elementary particles called mirror particles. This mirror universe has specific testable implications, especially in the domain of neutral particle oscillation, including neutron to mirror-neutron $nn'$ oscillation, which violates baryon number. Several experiments have been conducted to search for $nn'$ oscillation and have imposed very strong constrains on its parameters. Recent analyses of some of these experiments have identified anomalies that could suggest the detection of $nn'$ oscillation. Neutrons, owing to their large magnetic moment, precess upon the application of a magnetic field, and similarly, its mirror counterpart is also affected by the mirror magnetic field. Previous attempts to search for $nn'$ oscillation have involved (i) disappearance experiments, which isolated magnetic field dependent loss channel in ultracold neutron storage or transport, or (ii) reappearance experiments, which have searched for magnetic field dependent regeneration of neutrons across a barrier, that could only be traversed by a state invisible to the fundamental forces of the standard model, like the mirror neutron. However, $nn'$ oscillation also causes variations in the precession frequency of polarized neutrons upon flipping the direction of the applied magnetic field, which can be precisely measured by experiments searching for its electric dipole moment. The first such study [P. Mohanmurthy et al., Symmetry 14, 487 (2022)] to search for $nn'$ oscillation used data from the most recent neutron electric dipole moment measurement, compensated for the systematic effects that affect the ratio of precession frequencies of ultracold neutrons to cohabiting $^{199}$Hg-atoms, and constrained the $nn'$ oscillation to $\tau_{nn'}/\sqrt{\cos(\beta)} > 5.7~$s, $0.36~\mu\text{T}'

Speaker: Dr Prajwal MohanMurthy (Massachusetts Institute of Technology)

NStar-f_SPIN.pptx

11:45 AM Discussion

96 Hadronic parity violation in few-nucleon systems

Parity-violating interactions between nucleons are the manifestation of an interplay of strong and weak interactions between quarks in the nucleons. Compared to the dominant parity-conserving part, the parity-violating component of the nucleon-nucleon interaction is expected to be suppressed by approximately seven orders of magnitude or more. Due to the short range of the weak interactions, hadronic parity violation provides a unique probe of the strong dynamics that bind quarks into nucleons. An experimental program is mapping out this weak component of the nuclear force in few-nucleon systems. I will discuss theoretical progress based on effective field theory and large-$N_c$ methods to analyze and interpret hadronic parity violation in few-nucleon systems.

Speaker: Matthias Schindler (University of South Carolina)

Spin23_Schindler.pdf

12:10 PM Discussion

97 Is there evidence of strong parity violation in the proton?

We present a study of strong parity-violating contributions that can be included in inclusive Deep Inelastic Scattering (DIS) off an unpolarized proton target. We show that a non vanishing parity-violating structure function arise even in the case of pure photon exchange, in contrast with standard results.
The size of the additional strong parity-violating term is estimated by fitting available experimental data on electron and positron beam-spin asymmetries.

Speaker: Matteo Cerutti (University of Pavia)

Cerutti_SPIN23_adobe.pdf

Cerutti_SPIN23_preview.pdf

12:35 PM Discussion

Joint GPD/Future: Joint GPD Future II

Convener: Charlotte Van Hulse (UAH)

98 Exclusive Lepton Pair Production at the Electron-Ion Collider

The two-photon exclusive production of lepton pairs at the Electron-Ion Collider will open interesting research directions thanks to a very high luminosity and clean experimental conditions. A survey of the scientific potential of such studies is reported. In particular, we consider unique measurements of the proton elastic electromagnetic form-factors.

https://link.springer.com/article/10.1140/epjc/s10052-022-10820-0

Speaker: Krzysztof Piotrzkowski (AGH UST)

Exclusive_Lepton_Pair_Production_at_the_Electron_Ion_Collider__SPIN23.pdf

99 Future measurements of TCS at JLab Hall C

In this talk, we will discuss future experiments we are developing for measuring Timelike Compton Scattering (TCS) at JLab Hall C. The first experiment will measure transversely polarized target spin asymmetries off a NH$_{3}$ target. The second one is using an unpolarized hydrogen target and a circularly polarized photon beam, aiming at a high statistics measurement of TCS unpolarized and beam polarized cross sections. Our goal is to access the Generalized Parton Distributions (GPDs) H, H̃ and E. GPD E, poorly constrained, contains information about the orbital momentum of the quarks, and can be constrained with the first experiment. The main goal of the second experiment is to compare GPDs extracted from TCS (timelike process) to GPDs extracted from DVCS (Deeply Virtual Compton Scattering, spacelike process), to test GPDs universality. We will present these experiments, our goals, and projected results.

Speaker: Debaditya Biswas (Virginia Tech)

SPIN_23_TCS_BISWAS.pdf

100 Can we measure Double DVCS at JLab and the EIC?

Generalized parton distributions (GPDs) are off-forward matrix elements of quark and gluon operators that enclose information on the total angular momentum of partons, and so on the spin of hadrons (cf. EMC measurements and spin puzzle). In addition, GPDs enable tomography of the nucleon allowing to study spatial distribution of partons as a function of their momentum. To access GPDs one needs to consider exclusive processes, such as deeply virtual and timelike Compton scattering (DVCS and TCS). At LO these processes are mainly sensitive to GPDs in a restricted kinematic domain, this is $x = \xi$, where $x$ represents the average fraction of longitudinal momentum carried by an active parton, while $\xi$ is the so-called skewness variable. The process that avoids this constraint is double deeply virtual Compton scattering (DDVCS) for which an electron scatters off a nucleon and produces a lepton pair. The extra virtuality with respect to DVCS and TCS allows for LO access to GPDs at $x\neq\xi$.

In this talk, the importance of DDVCS for GPD physics, key objects for the understanding of the hadron's spin, will be highlighted. Elements of impact studies for current and future experiments at facilities such that the Electron-Ion Collider (EIC) and JLab have been worked out by means of the PARTONS software and the EpIC Monte Carlo event generator. For this purpose, a new formulation of DDVCS based on the spinor techniques by R. Kleiss and W. J. Stirling (1980s) was developed and will be shown as well.

Speaker: Victor Martinez-Fernandez (National Centre for Nuclear Research (NCBJ))

spin2023_slides_2023_VMF.pdf

101 DDVCS experiment in Hall A at Jefferson Lab

Double deeply virtual Compton scattering (DDVCS), corresponding to the scattering of a virtual photon off a quark, followed by the emission of a photon of a different virtuality (decaying into leptons), allows for a unique access to the Generalized Parton Distributions (GPDs) in the ERBL region. The main advantage of DDVCS is enabling the decorrelation between the x and $\xi$ dependence of GPDs , which is essential for tomographic interpretation, relying on their extrapolation to zero skewness. In this talk we will present our projections and experimental setup for a DDVCS experiment at JLab using the Solid spectrometer in Hall A and an 11 GeV electron beam. We will also discuss the potential and opportunities for DDVCS experiments at JLab Hall A/C.

Speaker: Marie BOER (Virginia Tech)

mboer_SPIN2023_DDVCS.pdf

Joint Nuclear/Heavy Ion

Convener: Ian Cloet (Argonne National Laboratory)

102 Measurements of Vector Meson Global Spin Alignment in Heavy-Ion Collisions at RHIC (Invited Talk)

STAR collaboration observed a global spin alignment of φ-mesons in Au+Au collisions using the data from the first phase of the RHIC Beam Energy Scan program (BES- I) [1]. This cannot be explained by conventional mechanisms but may be attributable to the influence of vector meson force fields. In this talk, we present new measurements of vector meson global spin alignment by the STAR collaboration, including φ-mesons using higher-statistics Au+Au data at $\sqrt{s_{NN}}$ = 7.7, 14.6, and 19.6 GeV from the BES-II program, φ, ω, and J/ψ-mesons in Au+Au, Ru+Ru, and Zr+Zr collisions at $\sqrt{s_{NN}}$ = 200 GeV. These differential global spin alignment measurements of vector mesons with various constituent quarks can help understand the roles of the vector meson force field, medium evolution, and hadronization mechanisms in global spin alignment.

[1] STAR Collaboration. Nature 614, 244248 (2023)

Speaker: Gavin Wilks (STAR Collaboration, University of Illinois at Chicago)

WilksGavin_SPIN2023_v6.pdf

103 Transverse Λ and anti-Λ Hyperon Polarization Measurements at LHCb

Transverse $\Lambda$ (uds) polarization observed over four decades ago contradicted expectations from early leading-order perturbative QCD calculations. Measurements of $\Lambda$ polarization from unpolarized pp and pA collisions have been previously observed to increase as a function of $x_F$ and $p_T$ up to a few GeV range and approximately independent of beam energy. Recent studies have linked polarization to the process of hadronization, which describes how particular hadrons are formed from scattered quarks and gluons. The high energy of the LHC and the coverage and precision measurement possibilities from LHCb's forward geometry are ideal for studying hyperon polarization as a function of both $p_T$ and $x_F$. The status and prospects of $\Lambda$ and $\bar{{\Lambda}}$ polarization measurements in pp, pPb, Pbp, and fixed-target pNe collisions at LHCb will be presented.

Speaker: Cynthia Nunez (University of Michigan)

CynthiaNunez_SPIN2023.pdf

104 Studying high $p_T$ momentum azimuthal anisotropies in unpolarized proton-proton collisions using transverse momentum dependent (TMD) parton distribution and fragmentation functions

Unpolarized protons can generate transversely polarized quarks or linearly polarized gluons through a distribution known as the Boer-Mulders' function. The fragmentation of similarly polarized partons to unpolarized hadrons is called the Collins' function. Both of these functions include correlations between the spin or polarization and the relative transverse momentum of the incoming or outgoing parton, with respect to the parent or final hadron.

We explore the effect of including these and other Transverse Momentum Dependent (TMD) distributions on the production of high-$p_T$ (unpolarized) hadrons from (unpolarized) proton-proton scattering. The resulting initial state anisotropies, coupled with similar final state effects, may account for the observed azimuthal anisotropy of the produced high transverse momentum hadrons, without modification to the angle integrated spectra. This may be an explanation for the existence of a $v_2$ in high-$p_T$ hadron spectra in $p$-$A$ collisions without any observable nuclear modification of the spectra.

Speaker: ismail soudi (Wayne State University)

Anisotropy_highpT_Ismail_Soudi.pdf

105 Discussions

Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy IV

Convener: Alexandre Deur (Thomas Jefferson National Accelerator Facility)

106 Properties of the newly discovered exotic particles in Diquark model.

{\bf Abstract}
\vskip .2in

Recently CERN has discovered three new exotic particles in LHCb. The particle are $T_{cso}$ $(2900)^{++}$, a doubly charged tetraquark with quark configuration (csu$\overline{d}$), $T_{cso}$ $(2900)^{0}$, a neutral tetraquark with quark configuration (cds$\overline{u}$) and a neutral pentaquark $P_{\psi s}$ $(4338)^{0}$ with quark configuration (c$\overline{c}$ uds) which is first observed pentaquark with a strange quark in its configuration. The discovery of these subatomic particles are exciting and the nature of interaction of the constituent quarks are need to be understood for these multiquark states. Diquark is one of the most important candidate for studying the structure and dynamics of exotic states. In the current work we have studied the properties of these particles in the frame work of diquark correlation. Diquark is a hypothetical coloured antisymmetric correlation of two quarks with spin 0 (scalar) or a vector with spin 1. We have suggested two models for diquarks. The composite fermion model and effective mass approximation model for diquark have been used to estimate the masses of $T_{cso}$ $(2900)^{++}$, $T_{cso}$ $(2900)^{0}$ and $P_{\psi s}$ $(4338)^{0}$. Results are found to be in good agreement with the experimental masses observed by CERN. We have also studied the higher states masses of the particles in the framework of the flux tube model which may be discovered in future. The regge trajectories are plotted. The form factor of these three exotics are also studied and plotted with different values of momentum transfer $Q^{2}$.

Speaker: Prof. Aparajita Bhattacharya (Adamas University)

107 A Measurement of Neutron Recoil Polarization in Deuteron Photodisintegration

An upcoming experiment at the High Intensity Game Source (HIGS) at the Triangle Universities Nuclear Laboratory (TUNL) will measure the polarization of recoiling neutrons from the photodisintegration of deuterium nuclei. As the simplest, multi-body nucleus, the deuteron offers a unique opportunity to study nucleon-nucleon interactions. Over the years, nuclear theory has developed to be able to describe the behavior and structure of few-body nuclei fairly well. However, discrepancies between theory and experimental data persist in measurements of certain polarization observables. The recoil polarization in $d(\gamma, \vec{n})p$, is a prime example of one such measurement. Historical data depart from modern theoretical calculations around a photon energy of 12 MeV. This experiment will map the polarization transfer over a range of photon energies below 20 MeV and neutron scattering angles. The setup consists of a set of high pressure $^{4}$He-Xe polarization analyzers surrounded by neutron scintillation counters to measure the recoil neutron polarization. From this measurement, the polarized and unpolarized photon beam contributions will be extracted and compared to theory. Preliminary analysis and results will be presented.

Speaker: Thomas Krahulik (University of Virginia)

Spin2023_TKrahulik.pdf

108 Use of the HIFROST Dilution Refrigerator for the T20 Experiment

I will discuss the importance of the T20 quantity and the basic experimental setup for a measurement of d (γ, n). Multiple measurements have suggested the existence of a channel around 9 MeV above the two nucleon masses in the center of mass frame. This diverges from calculations from current nuclear theory, and this experiment will focus on this new channel and yield information on the nature of any discrepancy. This experiment will immediately follow the experiment on the GDH measurement of the deuteron and use a lot of the same equipment. While the target will be polarized in the GDH experiment, the target will have the tensor component enhanced for the T20 experiment. I will discuss the status of the experiment, as well as the current status of the dilution refrigerator, and the progress being made.

Speaker: Matthew Roberts (University of Virginia)

SPIN 2023 Talk.pptx

Nucleon Helicity Structure: Helicity IV

Convener: Andrey Tarasov (North Carolina State University)

109 Quasi Parton Distribution Functions in the Covariant Parton Model

Quasi parton distribution functions (QPDFs) are defined in terms of QCD fields at spacelike separations evaluated in matrix elements of hadrons moving with velocity v. These objects can be studied in lattice QCD. In the limit when v approaches the speed of light, QPDFs converge in PDFs. It is insightful to study QPDFs and their convergence in models. In this work, we first study the QPDFs in a broad class of quark models characterized by one common feature, namely the absence of gauge degrees of freedom. We provide general proofs for the convergence and sum rules of the unpolarized quark and antiquarks QPDFs exploring both options γ0 and γ3. We choose the Covariant Parton Model (CPM) to illustrate our results. We derive analytical results for the small-x behavior of QPDFs and the energy-momentum tensor form factor at zero momentum transfer in the CPM. These results are of interest as they correspond to the Wandzura-Wilczek approximation.

Speaker: Fatma Aslan (Jefferson Lab/ University of Connecticut)

SPIN2023_ASLAN.pdf

110 Measurement of flavor asymmetry of light-quark sea in the proton at FNAL-SeaQuest

The SeaQuest experiment at Fermilab is designed to detect the Drell-Yan process in $p+p$ and $p+d$ reactions using the 120 GeV proton beam from the FNAL Main Injector in a fixed-target arrangement. SeaQuest recently observed a large $\bar{d}(x)/\bar{u}(x)$ asymmetry up to Bjorken $x$ as large as 0.45. The mechanism of this asymmetry has been studied via various theoretical models, and it was noted that the asymmetry of unpolarized distributions can be correlated with that of helicity distributions. As an example, the statistical model predicts a similar magnitude of $\bar{u}(x)$ and $\bar{d}(x)$) with the opposite sign, such that $\bar{d}(x) - \bar{u}(x) \approx - \left(\Delta\bar{d}(x) - \Delta\bar{u}(x)\right)$. The latest results from SeaQuest using an updated and higher precision measurement on the anti-quark flavor asymmetry will be presented.

Speaker: Kenichi Nakano (University of Virginia)

SPIN2023_KenichiNakano.pdf

111 Update on the nucleon quark distribution functions calculation with a confining NJL model adding pseudoscalar and vector diquarks

We present an update on the calculation of nucleon quark distribution functions using a confining Nambu-Jona-Lasinio (NJL) model. Originally developed for nucleons, the NJL model is now seen as an effective theory of low-energy QCD that is based on quark degrees of freedom. The nucleon bound state is obtained by solving the Faddeev equation in the quark–diquark approximation, where we include not only the scalar and axial vector diquark channels but also the pseudoscalar and vector diquarks. We present the results of our calculations for the unpolarized and polarized quark light-front momentum distribution functions and compare them to the available empirical parametrizations.

Speaker: Bailing Ma (Argonne National Lab)

talkSPIN2023BailingMa.pdf

Polarized Ion and Lepton Sources and Targets: Sources and Targets IV

Convener: Todd Averett (W&M)

112 A High-Magnetic-Field Polarized 3He Target for JLab's CLAS12

Polarized $^3$He nuclear targets have been invaluable surrogates for polarized neutron targets in spin-dependent scattering studies of the quark and gluon structure of matter. Traditional polarized $^3$He targets have seen dramatic improvements in the last three decades, however they have been limited in their use in spectrometers that utilize high-magnetic-field tracking systems, such as Jefferson Lab's CLAS12 spectrometer. Developments in high-magnetic-field metastability exchange optical pumping of $^3$He, recently brought to bear for a polarized $^3$He ion source for RHIC and the EIC, offer a path to a high-field polarized $^3$He fixed target. By combining these techniques with a double-cell cryogenic target design, such as the one used for the MIT-Bates 88-02 experiment, polarization and target density comparable to traditional polarized $^3$He targets can be reached while within a high magnetic field environment. We will discuss the conceptual design for such a target and show our progress in this target's development.

Speaker: Dr James Maxwell (Jefferson Lab)

maxwell_spin_2023.pdf

113 Transversely Polarized Solid Target for Hall B at Jefferson Lab

The physics program for Hall B at Jefferson Lab includes multiple, high-impact experiments scattering electrons from transversely polarized protons. These experiments will measure, for example, the Transverse Momentum Distributions and the Generalized Parton Distribution for protons, using, respectively, semi-inclusive deep inelastic scattering and deeply virtual Compton scattering. In this talk I will discuss the technical challenges to implementing a polarized solid-state target in the Hall B experimental environment, examine potential solutions, and describe the current status of the target design.

Speaker: Chris Keith (Jefferson Lab)

ckeith_SPIN2023.pdf

114 Achieving High Deuteron Tensor Polarization For Polarized Target Experiments

Dynamic nuclear polarization (DNP) is technique used to enhance the nuclear spin polarization of materials. DNP works by using microwaves to continuously drive spin transitions in a material that is doped with free radicals, and placed inside a 1 K environment in a high magnetic field. Once enhanced, the nuclear polarization can be determined by analyzing the lineshape of the NMR absorption spectrum. This talk will describe the DNP system used at the University of New Hampshire, and explain novel techniques in inducing high tensor polarization in deuterium.

Speaker: Allison Zec (University of New Hampshire)

AJZ-SPIN2023.pdf

12:40 PM Lunch Break

3D Structure of the Nucleon: TMDs: TMDs V

Convener: Michael Engelhardt (NMSU)

115 Transverse Momentum Dependent Factorization at NLP

In this talk, I'll discuss our recent results on transverse momentum dependent factorization and resummation at sub-leading power in Drell-Yan and semi-inclusive deep inelastic scattering. In these processes, the sub-leading power contributions to the cross section enter as a kinematic power correction to the leptonic tensor, and the kinematic, intrinsic, and dynamic sub-leading contributions to the hadronic tensor. By consistently treating the power counting of the interactions, we demonstrate renormalization group consistency. We calculate the anomalous dimensions of the kinematic and intrinsic sub-leading correlation functions at one loop and find that the evolution equations give rise to anomalous dimension matrices which mix leading and sub-leading power distribution functions. Additionally we calculate the hard and soft functions associated with each of these contributions and find that they differ from those at leading power. In particular, we demonstrate that the one loop soft function associated with the intrinsic and kinematic sub-leading transverse momentum dependent distributions is one half of the leading power soft function. Finally, we calculate the rapidity anomalous dimension for the dynamic sub-leading distributions and find that it is the same as the leading power anomalous dimension. We then comment on the implications for the soft function associated with this contribution. Using this information, we establish the factorization formalism at sub-leading power for these processes at the one-loop level.

Speaker: John Terry (University of California, Los Angeles)

116 Transverse-momentum-dependent factorization at next-to-leading power

We present our results on transverse momentum dependent factorization and resummation at sub-leading power in Drell-Yan and semi-inclusive deep inelastic scattering. In these processes the sub-leading power contributions to the cross section enter as a kinematic power correction to the leptonic tensor, and the kinematic, intrinsic, and dynamic sub-leading contributions to the hadronic tensor. By consistently treating the power counting of the interactions, we demonstrate renormalization group consistency. We calculate the anomalous dimensions of the kinematic, intrinsic, and dynamical sub-leading correlation functions at one loop and find the evolution equations. Additionally we calculate the hard and soft functions associated with each of these contributions and and compare them to the leading power results. We also calculate the one loop soft function associated with the intrinsic and kinematic sub-leading transverse momentum dependent distributions and compare them to the leading power results. Using this information, we establish the factorization formalism at sub-leading power for these processes at the one-loop level. We also focus on the matching of the large and small transverse momentum contributions in semi-inclusive deep inelastic scattering processes and Drell Yan. We pay special attention to azimuthal modulations of unpolarized cross sections such as the Cahn effect. Finally we present our findings on the QCD equation of motion relations beyond tree level.

Speaker: Leonard Gamberg (Penn State Berks)

Gamberg_SPIN_23_f.pdf

117 Unpolarised Semi-Inclusive DIS at COMPASS

Non-zero transverse momentum of partons and its possible correlation with partonic spin is reflected in the distributions of the transverse momentum $P_T$ and azimuthal angle $\phi$ of hadrons produced in deep inelastic scattering (DIS). Assuming Gaussian dependence of transverse momentum dependent (TMD) PDFs and fragmentation functions (FFs) upon quark transverse momentum, an exponential distribution of $P_T^2$ is expected. For an unpolarised nucleon, three azimuthal modulations that can be related to combinations of twist-two or higher-twist TMD PDFs and FFs arise: the $\cos\phi$ modulation related to the so-called Cahn effect, the $\cos2\phi$ term related to the Boer–Mulders PDF and the $\sin\phi$ modulation known as beam-spin asymmetry.
In 2016 and 2017, the COMPASS collaboration at CERN collected tens of millions SIDIS events using a longitudinally polarised 160 GeV/$c$ muon beam scattering off a liquid hydrogen target. The $P_T^2$ distributions and the amplitudes of the aforementioned azimuthal modulations for charged hadrons have been extracted from part of the data. Radiative effects have been investigated using Djangoh MC generator. The results qualitatively agree with earlier COMPASS measurements with an isoscalar target.

Speaker: Jan Matoušek (Charles University (Prague, CZ))

Matousek_20230926.pdf

118 Current status of the neutral pion multiplicity studies at CLAS12.

Multiplicity studies are a fundamental measurement of particle physics, detailing the production fraction of a particle species within a more general particle process. Studies of hadron multiplicities within Semi-Inclusive Deep Inelastic Scattering (SIDIS) use the non-perturbative generation of hadrons from lepton-nucleon scattering to delve into nature of the hadronization process. Being that this process is the convolution of the perturbative electromagnetic hard scattering cross section, and the non-perturbative quark parton distributions and fragmentation functions, multiplicity studies can help reveal information about the non-perturbative structure of the proton. Moreover, the transverse momentum of the final state hadrons provides insight into the transverse momentum and spin of the fragmenting partons. Neutral pion production, unlike charged pion case, is not expected to have any major physics backgrounds, such as diffractive vector meson, semi-exclusive hadron production, or longitudinal photon contributions, and can provide a unique tool to directly study the production of hadrons. This work involves the SIDIS production of neutral pions at CLAS12, the CEBAF Large Acceptance Spectrometer for 12 GeV, where a 10.6 GeV electron beam was scattered off a fixed liquid hydrogen target in the Fall of 2018. We present the current status of the neutral pion multiplicity studies at CLAS12.

Speaker: Marshall Scott (ANL)

scott_spin_2023.pdf

119 Exploring fracture functions with semi-inclusive target- and double-spin asymmetries in the target fragmentation region with CLAS12

We report preliminary results on semi-inclusive target- and double-spin asymmetries where a proton is detected in the target-fragmentation region (TFR) in coincidence with the scattered electron. Compared to the current fragmentation region (CFR), where final state hadrons are produced by the struck quark, the TFR, where hadrons form out of the fragmenting spectator partons, is relatively little studied. The study of the formation of hadrons out of the target remnant can provide critical information on nucleonic structure and the process of hadronization through objects called fracture functions. Fracture functions are the TFR analog of the parton distribution functions defined in the CFR and, at leading twist, have the probabilistic interpretation of forming a specific hadron from a fragmenting nucleon after the emission of a particular quark. The data were taken with a 10 GeV longitudinally polarized electron beam incident on a longitudinally polarized NH$_3$ target using the CLAS12 Spectrometer in Hall B of Jefferson Lab. These data represent the first signifiant opportunity to measure structure functions such as $F_{UL}$, $F_{LL}$ and others in the TFR and provide the possibility of mapping out the transition between both regions of kinematic origin as well as serving as a test of the fracture function formalism by linking the observed fracture function-dependent quantities to the more traditional CFR observables through momentum sum rules.

Speaker: Timothy Hayward (University of Connecticut)

Hayward_SPIN-2023_RGC_epX_talk.pdf

Acceleration, Storage and Polarimetry of Polarized Beams: Acceleration I

Convener: Hiromi Iinuma

120 An Overview of Helions in the HSR and its Injectors

The Electron Ion Collider calls for polarized helion on polarized electron colli-
sions. These collisions will require 1.2×10^11 ions per bunch at 70% polarization.
Polarized helions will originate from the Electron Beam Ion Source and be in-
jected into the Booster at |Gγ| = 4.1932. The injected intensity from EBIS is
expected to be 2×10^11 ions with a polarization of 80%. Meeting the EIC physics
requirements will require maintaining both high efficiency and high polarization
transmission through the accelerator complex. In the Booster, an AC dipole
will be used to spin-flip across intrinsic resonances and harmonic corrections
will be used for imperfection resonances, up to extraction at |Gγ| = 10.5. In
the Alternating Gradient Synchrotron, due to the higher anomalous G-factor
of helions, the two partial snakes will have sufficient rotation to facilitate both
horizontal and vertical betatron tunes being placed inside the spin-tune gap up
to |Gγ| = 49.5. In the Hadron Storage Ring, 6 full snakes will be used to min-
imize polarization loss up to a maximum energy of |Gγ| = 820. At collisions,
longitudinal polarization will be available through use of helical spin rotators.
This paper provides a summary of polarized helion transmission from injection
to the Booster to top energy in the Hadron Storage Ring.

The work is supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.

Speaker: Kiel Hock (BNL)

OverviewOfHelionsHSRandInjectors_KHOCK.pdf

121 EIC's HSR Rotator and Snake Swap Study

The Electron-Ion Collider's Hadron Storage Ring (HSR) will use a pair of spin rotators to achieve longitudinal polarization at IP6. Additionally there are to be six snakes located at azimuthal angles of 60 degrees from each other. Due to space constraints in the whole lattice, in order to achieve a 60 degree separation between the snakes, we are forced to place a snake near IP6 where the rotator normally would be. We explore if a powering scheme exists which would recover a longitudinal polarization at IP6 and the same spin rotation of a normal orthogonal snake at collision energies.

Speaker: Vahid Ranjbar (BNL)

Spin2023SnakeRot.pptx

122 The Polarized Hydrogen Gas Jet Target. From RHIC to EIC.

At the Relativistic Heavy-Ion Collider (RHIC), the Polarized Hydrogen Gas Jet Target Polarimeter (HJET) is used to measure absolute transverse (vertical) polarization of the proton beams with low systematic uncertainties of about $\sigma^\text{syst}_P/P\le0.5\%$. HJET performance has been thoroughly studied in measurements of the ${pp}$ and ${pA}$ analyzing powers for a broad range of proton and ion beam energies (4--250 GeV/nucleon). Based on these results, HJET was suggested for proton beam polarimetry (with a required accuracy of 1\%) in the future Electron-Ion Collider (EIC). Here, the possibility of using HJET to measure the $^3$He ($h$) beam polarization at EIC will be considered. The experimentally determined ratio of the beam and target spin assymetries used to calculate the beam polarization must be adjusted by the ratio of the $p^{\uparrow}h$ and $h^{\uparrow}p$ analyzing powers, which rely on unknown proton-helion hadronic spin-flip amplitudes. Since these amplitudes are small, the existing theoretical accuracy of the relations between proton-helion and proton-proton (which have been measured by HJET) hadronic spin-flip amplitudes is sufficient to obtain the beam polarization with the required precision. Another potential source of systematic uncertainty in the $^3$He beam polarization measurement is the helion breakup in scattering. It has been demonstrated that while the breakup can cause corrections to the spin-flip interference terms of up to 4\%, the effect cancels out to a negligible value in the analyzing power ratio. Detailed explanations for the results obtained will be discussed.

Speaker: Andrei Poblaguev (Brookhaven National Laboratory)

2023.09.26_SPIN23.pdf

123 Electron polarimetry at the Electron Ion Collider

The Electron Ion Collider (EIC) will make precision measurements of different asymmetries to shed light on nucleon structure and dynamics. One of the most important sources of systematic uncertainty is the determination of the degree of polarization of the electron beam. This talk will detail the challenges to electron polarimetry in this new machine and the current status for the Compton polarimeter. The focus will be on two aspects: the laser system and the detector package. The designed laser system will make use of different advances in the field to decrease systematics and increase radiation hardness of the system. The detection system will need to measure both a positional asymmetry and an energy asymmetry to fully disentable the polarization direction.

Speakers: Ciprian Gal (Jefferson Lab), Dave Gaskell (Jefferson Lab)

eic_electron_polarimetry_SPIN23.pdf

Future Facilities and Experiments: Future I

124 Probing the Sivers Asymmetry from light-sea quarks with the SpinQuest (E1039) experiment

The SpinQuest experiment (E1039) at Fermilab will measure the correlation between the angular distribution of the final-state di-muons and the spin-polarization of transversely polarized NH$_3$ (for proton) and ND$_3$ (for neutron) targets. The 120 GeV unpolarized proton beam of the Main Injector will be used to measure the Transverse Single Spin Asymmetry (TSSA) to quantify both the magnitude and sign of the Sivers functions for the sea quarks. Sea quark information in polarized nucleons is greatly lacking in global data and SpinQuest will provide critical insight into the sea quarks' role in partonic dynamics and composition. In addition to the Drell-Yan TSSA measurements, J/Psi TSSAs will also be measured to extract information on the gluon Sivers function. This presentation will provide an overview of the current status and forthcoming plans of the SpinQuest experiment.

Speaker: Ishara Fernando (University of Virginia)

SpinQuest_Talk_SPIN2023_IsharaFernando.pdf

125 Utilizing Machine Learning Pattern Recognition for Online Monitoring and Visualization in SpinQuest Experiment

SpinQuest will measure the sea quarks Sivers Asymmetry, a left-right

asymmetry, with a target transversely polarized with respect to the in-
coming 120 GeV proton beam. An online monitoring system has been

developed to scan the polarized target system and polarization data while
integrating information from detectors and event reconstruction for near
continuous quality checking of the incoming data. Online monitoring of
the target system and detector package will play a vital role in ensuring
optimal performance of the target while achieving the highest figure of

merit possible given the experimental circumstances. This novel moni-
toring system enhances the debugging process during commissioning and

data acquisition through the use of machine learning pattern recognition
techniques and anomaly detection. The scheme outlined promises to aid
target operators and shift takers during the two year long production runs
to begin in Fall of 2023 at Fermilab.

Speaker: Jordan Roberts (University of Virginia)

Spin2023-1.pdf

126 GPU-based Online Reconstruction for J/ψ TSSA at SpinQuest experiment

The E1039/SpinQuest experiment at Fermilab will measure the transverse single spin asymmetry (TSSA) in several processes such as $J/\psi$ production and Drell-Yan di-muon pair production, exploiting the 120 GeV unpolarized proton beam from the Fermilab Main Injector on transversely polarized ammonia and deuterated ammonia targets.
Such measurements are anticipated to provide knowledge on the Sivers function from the proton sea quarks and gluons.
The importance of the Sivers function studies is based on their ability to probe the orbital angular momenta of quarks and gluons, which may contribute significantly to the nucleon spin and thus help resolve the so-called ``proton spin puzzle''.
In pursuit of these asymmetry measurements, we have been developing and optimizing an online reconstruction algorithm exploiting the high throughput and mass parallelization capabilities of graphics processing units (GPU), which combined with adequate visualization tools will provide real-time data monitoring for the SpinQuest experiment.
This talk will highlight the SpinQuest experiment and the spectrometer efficiency induced projected systematic uncertainties for the $J/\psi$ TSSA from its first production data.
The performance metrics of the GPU-based online reconstruction algorithm will also be discussed, along with the features and methods employed to reach successful real-time data visualization.

This work is supported in part by the U.S. DOE award # DE-FG02-07ER41528

Speaker: Eric Fuchey (Mississippi State University)

EFuchey_Spin2023.pdf

Joint GPD/Nuclear: Joint GPD/Nuclear I

Convener: Zhoudunming Tu (BNL)

127 Gravitational form factors of nuclei

We compute the gravitational form factors of various nuclei in the Skyrme model. Based on https://arxiv.org/abs/2304.05994

Speaker: Yoshitaka Hatta (Brookhaven National Laboratory)

SpinSkyrme.pdf

128 Nuclear Geometry at high energy from exclusive vector meson production

Exclusive processes in Ultra Peripheral Collisions (UPCs) at the LHC and in the future EIC will provide access to the spatial distribution of small-x partons in nuclei at high energies. In particular, the transverse momentum of the produced particle, such as vector meson, is Fourier conjugate to the impact parameter.

In this talk, we focus on vector meson production in UPCs and show how non-linear saturation effects change the density profile of a heavy nucleus, and that such modifications are necessary to obtain a good description of the exclusive J/psi production as measured by the ALICE and LHCb collaborations in Pb+Pb UPCs at the LHC [1]. We employ the joint impact parameter and transverse momentum-dependent cross-section framework developed in [2] to incorporate the finite photon transverse momentum and the interference between the cases for which the role of photon emitter and target are interchanged between the nuclei. We show that these effects are comparable to the experimental precision for pT differential cross sections and must be included when comparing to LHC data.

[1] Heikki Mäntysaari, Farid Salazar and Björn Schenke.
Phys.Rev.D 106 (2022) 7, 074019. e-Print: 2207.03712 [hep-ph]

[2] Hongxi Xing, Cheng Zhang, Jian Zhou, Ya-Jin Zhou.
JHEP 10 (2020) 064 • e-Print: 2006.06206 [hep-ph]

Speaker: Farid Salazar (LBL/UCB/UCLA)

SPIN2023_Salazar.pdf

129 Vector meson photoproduction in UPC with ALICE

The ALICE Collaboration has studied photonuclear interactions in ultra-peripheral heavy-ion collisions to probe gluon dynamics of protons and nuclei in a new kinematic regime at the LHC.

Several new measurements will be presented, including the coherent J/ψ photoproduction cross section, measured as a function of the Mandelstam |t|, which provides constraints of models that consider the transverse profile of the target at very low Bjorken-x.

The polarization of coherent J/psi photoproduction has been measured
for the first time and found to be compatible with transverse polarization.

Both exclusive and, for the first time at LHC, dissociative J/ψ photoproduction cross section have been measured in proton targets.

Finally, the energy dependence of the photonuclear cross section is presented for photon-nuclear energies from 17 GeV up to 920 GeV and for the Bjorken-x down to $10^{−5}$, exploring a new regime of super dense gluons.

Speaker: valeri pozdnyakov

PozdnyakovV.pdf

130 Polarisation-dependent studies of exclusive J/psi production in hadron-hadron and lepton-hadron interactions

We studied polarisation-dependent exclusive J/ψ production in ultraperipheral heavy-ion collisions at RHIC and LHC energies and in eA collisions at EIC energies, in the framework of color glass condensate effective theory. The azimuthal averaged J/ψ production cross section measured by STAR and ALICE is accurately described by our calculation. We further predict significant cos 2ϕ and cos 4ϕ azimuthal asymmetries both in UPCs and in eA collisions, which are attributed to the linearly polarized photon, the double-slit interference effect in photonuclear reactions, and the final state soft photon radiation effect. This study may provide further information on limiting gluon transverse spatial distribution inside large nuclei.

Speaker: Dr Yajin Zhou (Shandong University, China)

SPIN2023 YZ.pdf

Nucleon Helicity Structure: Helicity V

Convener: Sebastian Kuhn (Old Dominion University)

131 Recent Updates from the JAM Collaboration on Helicity PDFs

We present the latest global QCD analysis results from the Jefferson Lab Angular Momentum (JAM) collaboration on helicity PDFs. We focus on the light quark sea asymmetry, including in the analysis the latest $W$-lepton production data from the STAR collaboration at RHIC, as well as the sign of the gluon's helicity, including the latest jet production data from RHIC. We find a nonzero sea asymmetry and that current experimental data is not able to determine the sign of the gluon's helicity without constraints from theory.

Speaker: Christopher Cocuzza (Temple University)

SPIN2023.pdf

132 Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at $\sqrt{s}$ = 510 GeV in $\vec{p}+\vec{p}$ Collisions at PHENIX

Understanding the contribution of gluons to the spin of the proton is crucial for unraveling the proton spin puzzle. This has been one of the primary motivations behind the spin program conducted at the Relativistic Heavy Ion Collider (RHIC). The longitudinal spin structure of the proton is probed by colliding two protons with longitudinal polarization ($\vec{p}+\vec{p}$) and measuring the double-helicity asymmetry ($A_{LL}$) of the final-state particles such as hadrons, jets, and direct photons. While the measurements of hadrons and jets already indicate a nonzero gluon-spin contribution, it remains inconclusive whether the gluon spin positively or negatively contributes to the overall proton spin.

On the other hand, the direct-photon production, mainly originating from quark-gluon Compton scattering, provides a suitable channel to investigate the sign of the gluon-spin contribution. Additionally, the direct-photon production involves minimal fragmentation contributions, making it the ``cleanest'' channel when compared to hadron and jet production. However, there is a significant background of photon contributions from $\pi^0\rightarrow\gamma\gamma$ decays, which need to be identified by reconstructing the invariant mass of the two decay photons. At RHIC, only the electromagnetic calorimeter at PHENIX is capable of reconstructing the two decay photons of $\pi^0$ up to approximately 30 GeV/c of photon transverse momentum.

In this presentation, I will present the measurements of the direct-photon cross-section and $A_{LL}$ at a center-of-mass energy of $\sqrt{s}$ = 510 GeV in $\vec{p}+\vec{p}$ collisions at PHENIX. The results of our $A_{LL}$ measurement strongly support calculations that include positive gluon-spin contributions.

Speaker: Zhongling Ji (UCLA)

Zhongling_Ji_Direct_Photon.pdf

133 Longitudinal double spin asymmetry of $\Lambda$, $\bar{\Lambda}$, $K_S^0$ and inclusive jets with high-$z$ $\pi^{\pm}$ tagging in polarized proton-proton collisions at $\sqrt{s}=200$ $\rm{GeV}$ at STAR

Understanding the origin of the proton spin is one of the most fundamental and challenging questions in QCD. Much progress has been made since the first surprising result by the EMC experiment in the late 1980s. However, the helicity distributions of strange quarks and anti-quarks inside the proton are still not well constrained by the experimental data. Measurement of the longitudinal double spin asymmetry, $A_{LL}$, of $\Lambda$, $\bar{\Lambda}$ and $K_S^0$ in the longitudinally polarized proton-proton collisions may shed light on the strange quark and anti-quark helicity distributions. In addition, the $A_{LL}$ of the inclusive jets tagged with a $\pi^+/\pi^-$ carrying high jet momentum fraction, $z$, in proton-proton collisions can provide further constraints on the gluon helicity distribution in the proton.
In this talk, we will present the status of the $A_{LL}$ measurements of $\Lambda$, $\bar{\Lambda}$ and $K_S^0$, and the inclusive jets tagged with a high-$z$ $\pi^{\pm}$. We will utilize the longitudinally polarized proton-proton collisions at $\sqrt{s}=200$ $\rm{GeV}$ collected by the STAR experiment with an integrated luminosity of about 52 $\mathrm{pb^{-1}}$

Speaker: Yi Yu

SPIN2023_YiYu.pdf

Polarized Ion and Lepton Sources and Targets: Sources and Targets V

Convener: Chris Keith (JLab)

134 Recent activities of the Bonn Polarized Target Group

The polarized target is an essential part of the experimental program at the Bonn accelerator facility ELSA. In recent years, the polarized target has been successfully used in various experiments to measure single and double polarization observables at the Crystal Barrel Detector at ELSA. Since our experimental program is limited to real photons, we use the classical frozen spin target technique (horizontal dilution refrigerator in combination with internal holding coils). Besides a reliable operation of the target, long relaxation times and high polarization values in proton and deuteron target materials have been achieved in the scattering experiments. I will present the activities of the Bonn Polarized Target Group, the current status and new developments of the group also with respect to the European research funding program CryPTA.

Speaker: Hartmut Dutz (Physikalisches Institut Universität Bonn)

Spin2023Dutz.pdf

135 The SpinQuest (E1039) experiment’s polarized target system

The SpinQuest experiment at Fermilab aims to measure the Sivers asymmetry for the light sea quarks in the longitudinal momentum fraction range of 0.1 < $x_B$ < 0.5 from the Drell-Yan process. A nonzero Sivers asymmetry measurement would be indicative of a nonzero orbital angular momentum contribution from the sea quarks. The SpinQuest experiment uses the proton beam from Fermilab’s 120 GeV main injector, which will provide about $10^{12}$ protons per second during a 4.4 seconds spill. The SpinQuest polarized target uses a superconducting split-pair magnet with an operating magnetic field of 5T with transversely polarized NH$_3$ or ND$_3$ targets (8cm long target cells). The maximum intensity that the target can handle will be determined during beam-target commissioning. As proposed SpinQuest will be the highest integrated luminosity around 2 x $10^{42} cm^{-2}$ ever on a solid polarized target. The helium-4 evaporation refrigerator operates at 1 Kelvin using high-powered evaporation from a roots stack with a pumping rate of nearly 17,000 $m^3$/hr. The anticipated average target polarizations of 80\% for protons and 32\% for deuterons will be measured using three NMR coils equally spaced apart in the target cell. An overview of the SpinQuest target system will be presented.

Speaker: Muhammad Farooq (National Centre for Physics, Islamabad, Pakistan, and University of Virginia, USA)

SpinQuest (E1039) Polarized Target.pdf

136 SpinQuest evaporation refrigerator

The SpinQuest polarized target system at Fermilab uses a continuous flow helium-4 evaporation refrigerator to provide the required cooling power during the dynamic nuclear polarization (DNP) process and the intense proton beam from the 120 GeV main injector. The refrigerator was designed in compliance with the American Society of Mechanical Engineers (ASME) to pass the cryogenic safety review required to operate at Fermilab. The large Oerlikon roots pump stack coupled to the refrigerator has a pump rate of $17000 \:m^3/h$ (two $8400\:m^3/h$ in parallel) backed with another $8400 \:m^3/h$ roots pump backed with an $840 \:m^3/h$ rotary vane pump. With such a high-powered backing pump a radiation-resistant flow control system is required near the target cryostat to regulate flow during target calibrations. A restricted flow around the roots path gate valve is fitted to the system to enable refrigerator flow control while the main roots path is closed. This flow control provides a warmer temperature range for thermal equilibrium calibration measurements necessary for the polarized target system. The ASME design and the refrigerator control system are presented in this talk.

Speaker: Mr Vibodha Bandara (University of Colombo , University of Virginia)

Spin2023_Vibodha_V2.pptx

3:30 PM Coffee Break

3D Structure of the Nucleon: GPDs and Form Factors: GPD III

Convener: Kyungseon Joo (University of Connecticut)

137 Exclusive photoproduction of a photon-meson pair: A new class of observables to probe GPDs

In this talk, I will discuss the exclusive photoproduction of a photon-meson pair with large $p_T$ as a channel to probe GPDs. Like other $2 \to 3$ exclusive processes, this channel allows us to better study the $x$-dependence of GPDs, unlike other $2 \to 2$ processes such as DVCS which give "moment-type" information. Moreover, it also gives the possibility to access chiral-odd GPDs at the leading twist, which is completely unknown experimentally. The computation of the amplitude is performed at leading order and leading twist. The various mesons we consider are charged pions, and rho mesons of any charge and polarisation. I will also discuss the possibility of measuring such processes at various experiments, namely JLab, COMPASS, future EIC and LHC in ultra-peripheral collisions. In particular, in collider experiments, the dependence of GPDs at small skewness ($<10^{-3}$) can be extracted. I will discuss our recent progress in computing $\pi^0 \gamma$ photoproduction, where gluonic GPD contributions enter, as well as the extension of the calculation to next-to-leading order.

Speaker: Saad Nabeebaccus (IJCLab)

nabeebaccus-SPIN2023.pdf

138 Exclusive photoproduction of open heavy flavor meson pairs

In this talk we present our results for the exclusive photoproduction of the $D$-meson pairs with large invariant mass. We perform evaluations in the collinear factorization framework and in the leading order of the strong coupling $\alpha_s$, expressing the cross-section in terms of generalized parton distributions (GPDs) of different parton flavors in the proton. We focus on the photoproduction of the pseudoscalar-vector pairs, like e.g. $ D^{\pm}D^{*\mp}, D^{0}\overline{D}^{*0}, D_{s}^{+}D_{s}^{*-}$​, which gets the dominant contribution from the chiral even GPDs of the target, and estimate the cross-section in the kinematics of the future Electron Ion Collider (EIC). In all channels the amplitude of the process obtains comparable contributions from gluons and only one of the light quark flavors. This finding signals that the process potentially could be used to single out the contributions of the individual chiral even GPDs of light flavors. We found that the process is mostly sensitive to the behavior of GPDs in the so-called Efremov-Radyushkin-Brodsky-Lepage (ERBL) region. Numerically, the cross-section of the process is sufficiently large for experimental studies and thus can be used as a complementary probe for studies of the partons GPDs.

This talk is partially based on materials presented in our recent arXiv preprint 2309.09748 [hep-ph].

Speaker: Marat Siddikov (Federico Santa Maria Technical University)

MSiddikov_SPIN2023.pdf

139 Exploring hadron structure with transition GPDs

Generalized parton distributions describe the non-forward matrix elements of QCD light-ray operators between hadronic states and unify the concepts of parton densities and hadron form factors. The concept can be extended to transitions between states with different hadronic composition, including multi-hadron states and resonances. These "transition GPDs" offer new opportunities for exploring the QCD structure of hadron resonances and have emerged as a field of study in its own right, with many recent results. This overview covers the concepts, methods, applications, and possible measurements. This includes: (a) Baryon transition GPDs $N \rightarrow \Delta$ and $N \rightarrow N^*$ from theoretical analysis ($1/N_c$ expansion of QCD) and DVCS experiments; (b) Transition matrix elements of QCD energy-momentum tensor and mechanical properties of baryon resonances; (c) Chiral-odd transition GPDs and exclusive pion/kaon electroproduction processes; (d) Near-threshold $N \rightarrow \pi N$ transition GPDs and chiral dynamics; (e) Hard exclusive processes and partonic operators as a new tool for hadron spectroscopy; (f) Prospects for experiments at JLab 12 GeV and EIC (far-forward detectors).

Speaker: Christian Weiss (Jefferson Lab)

weiss23_spin23_transition.pdf

140 N -> N* Transition Form Factors in Continuum QCD

One of the major challenges of modern theoretical and experimental hadron physics is to probe the Q^2 evolution of the transition form factors of a nucleon to its excited states in terms of the underlying fundamental degrees of freedom, namely, quarks and gluons. The pattern of their mass generation is firmly encoded in the non-perturbative solutions of the fundamental equations of motions of continuum QCD. A promising and systematically improvable theoretical effort along with the CLAS, CLAS12 and after potential increase of CEBAF energy up to 22 GeV will allow us to clearly and unequivocally understand and connect the long and short-range dynamics of QCD through charting out the evolution of these transition form factors with the probing photon momentum squared in electro-excitation processes. I will review the progress in this direction within joint effort between continuum QCD and experimental studies of the nucleon resonance electro-excitation amplitudes within the full range of distances where the transition from strongly coupled to perturbative QCD is expected.

Speaker: Adnan Bashir (University of Michoacan and Jefferson Lab)

Bashir-Duke-University-SPIN-23-1.pdf

Bashir-Duke-University-SPIN-23-1.pptx

141 The Backward Angle (u-channel) Exclusive Process at 12 GeV and Future EIC

The recent exclusive backward-angle electroproduction of mesons from Jefferson Lab electron-proton fixed-target scattering experiments hints on a new domain of applicability of QCD factorization in a unique u-channel kinematics regime. The interests of studying nucleon structure through u-channel meson production observables have grown significantly.

In the fixed target configuration, the u-channel meson electroproduction observables feature an unique interaction picture: target proton absorbs nearly all momentum induced by virtual photons and recoils forward; while the production mesons (such as omega or pions) are left behind almost at rest near the target station. At Jefferson Lab Hall C, the missing mass reconstruction technique is applied to resolve the produced nucleon; whereas in Hall B and D, the decayed mesons are directly detected. In this presentation, I will provide a summary on the key observations of the existing u-channel meson production results, update-to-date theory insights and a path to further explore u-channel observables from JLab 12 GeV Hall C program to the future Electron Ion Collider.

Speaker: Mr Wenliang Li (CFNS Stony Brook)

2023_SPIN_u_Channel_exclusive_processes.pdf

142 Threshold heavy quarkonium production and GPDs at large skewness

We present a theoretical update on the analysis of threshold heavy quarkonium e.g., $J/\psi$, production measurements. It has been shown that the such processes can be factorized with gluon generalized parton distributions (GPDs) which allow us to further connect to the gluonic gravitational form factors (GFFs) in the large $\xi$ limit. We will discuss the GPDs at large skewness with more details and present a more careful analysis.

Speaker: YUXUN GUO (University of Maryland)

Yuxun_JPSI_SPIN2023.pdf

3D Structure of the Nucleon: TMDs: TMDs VI

Convener: Alessandro Bacchetta (University of Pavia and INFN Pavia)

143 TMD phenomenology with the HSO approach

TMD observables are normally expressed in terms of their contributions coming from different regions in transverse momentum. The low transverse momentum is often ascribed to an intrinsic non perturbative property of the hadron, described by TMD factorization, while the large transverse momentum region can be computed using fixed order collinear perturbation theory. In the middle region, often called the matching region, the two techniques fail to provide a satisfactory interpolation resulting in significant tension. The standard techniques used in high-energy physics don't carry over for moderate hard scales spoiling the hadronic structure interpretation. A recent approach, designed to retain this physical interpretation, significantly alleviates this tension by providing phenomenologists and model builders with a very general tool to incorporate both perturbative and non perturbative contributions in the parametrization of TMD densities while guaranteeing the matching in the large transverse momentum region.

Speaker: Tommaso Rainaldi (Old Dominion University)

Rainaldi_SPIN2023.pdf

144 The many roles of triplet P zero quark antiquark pairs in nonperturbative QCD

Non-perturbative chromodynamics involving orbital angular momentum in confined systems of quarks and gluons can be studied in resonance decay, in flux ruptures of QCD jets, and in the virtual corrections to proton structure. Triplet P zero quark antiquark pairs contribute to many aspects of complex dynamical systems and emergent structures in quantum field theory.

Speaker: Dennis Sivers (Portland Physics Insitute)

SPIN2023_Sivers.pdf

SPIN2023_Sivers.pptx

145 Quark orbital angular momentum in the proton from a twist-3 generalized parton distribution

Quark orbital angular momentum in the proton is evaluated via a Lattice QCD calculation of the second Mellin moment of the twist-3 generalized parton distribution $\widetilde{E}_{2T} $ in the forward limit. The connection between this approach to quark orbital angular momentum and approaches previously utilized in Lattice QCD calculations, via generalized transverse momentum-dependent parton distributions and via Ji's sum rule, is reviewed. This connection can be given in terms of Lorentz invariance and equation of motion relations. The calculation of the second Mellin moment of $\widetilde{E}_{2T} $ proceeds via a finite-momentum proton matrix element of a quark bilocal operator with a straight-line gauge connection and separation in both the longitudinal and transverse directions. The dependence on the former component serves to extract the second Mellin moment, whereas the dependence on the latter component provides a transverse momentum cutoff for the matrix element. Furthermore, a derivative of the matrix element with respect to momentum transfer in the forward limit is required, which is obtained using a direct derivative method. The calculation utilizes a clover fermion ensemble at pion mass 317 MeV. The resulting quark orbital angular momentum is consistent with previous evaluations through alternative approaches, albeit with greater statistical uncertainty using a comparable number of samples.

Speaker: Michael Engelhardt (NMSU)

talk.pdf

146 Nucleon Energy-Energy Correlator in Lepton-Ion Collisions

In this talk, I will introduce the concept of the nucleon energy energy correlator (neec),which is a new way to study nucleon intrinsic dynamics. I will argue how this quantity can be measured in the dis process and present the NLL results.

Speaker: Haotian Cao

1_HTC_SPIN2023.pdf

147 Polarized jet anisotropy at the future Electron-Ion Collider

In this work, we study the azimuthal anisotropy of the back-to-back lepton-jet production in polarized lepton-proton collisions. This process defines three azimuthal angles: $\phi _S$ of the transverse spin $\boldsymbol{S}_T$ of the incident proton, $\phi _q$ of the transverse momentum imbalance $\boldsymbol{q}_T$ between the lepton and the jet, and $\phi _J$ of the jet transverse momentum. In particular, we provide the theoretical origins for the dependencies on $\left({\phi _q - \phi _J}\right)$ from a factorization formalism derived within the SCET framework. In addition, we present the numerical results of polarized azimuthal anisotropy related to the Sivers and worm-gear functions at EIC kinematics, showing that the interplay among the three azimuthal angles can create intriguing pictures.

Speaker: Dr Fanyi Zhao (UCLA,MIT)

SPIN2023-Fanyi.pdf

Acceleration, Storage and Polarimetry of Polarized Beams: Acceleration II

Convener: Oleg Eyser (BNL)

148 A New Level of Accuracy for Electron Beam Polarimetry at Jefferson Lab

The upcoming parity-violating physics program in Hall A at Jefferson Lab including MOLLER and SoLID require 0.4% accuracy separately for both Compton and Møller polarimeters. Each of these requires reaching a level of precision and accuracy not yet attained in published results for polarimeters of these types. An ongoing program to reach these goals has resulted in improvements in both the hardware and understanding of the devices and the systematic errors involved in their use. I will briefly discuss the efforts on both polarimetry fronts and examine why our teams are optimistic that this goal is within reach two years from now.

Speaker: Dr Donald Jones (Jefferson Lab)

SPIN2023polarimetry.pptx

149 Measuring Photon Beam Polarization Through Detection of $e^+e^-$ Pairs at GlueX

The Charged and Neutral Pion Polarizability Experiments (CPP and NPP) at GlueX require a precision measurement of the linear polarization of the incident photon beam.The utilization of electron-positron ($e^+e^-$) pair production is a valuable technique for determining photon beam polarizations.Polarization determination from pair production on atomic electrons (the Triplet Polarimeter, TPOL technique) or on a nuclear target with the detection of a single lepton are reliable methods to this end. This talk will show a new technique and the subsequent result for measurement of linear beam polarization through detection of $e^+e^-$ pairs in the GlueX forward drift chambers and calorimeters. The analyzing power for the azimuthal distribution of $e^+e^-$ pairs accessible within GlueX kinematics is approximately $60\%$. Using a neural net designed for $e/\pi$ separation, the spring 2018 GlueX data set was analyzed and measured to have an average beam polarization of $0.349 \pm 0.009$. This result agrees with the TPOL measurement of polarization within $0.85$ standard deviations. This technique to derive linear beam polarization from $e^+e^-$ pairs obtained during data taking can be applied to photo-production experiments where detection of $e^+e^-$ pairs is achieved with good particle identification and good angular acceptance in the forward angles. This work was supported in part by the U.S. Department of Energy award DE-FG02-88ER40415 and by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.

Speaker: Albert Fabrizi

AFabrizi_BHPairPolarimetryAtGlueX_SPINTalk_TuesSep262023.pdf

150 Status of the 5 MeV Mott polarimeter at MESA

Parity-violating experiments like P2 at Mainz Energy-Recovering Superconducting Accelerator (MESA) demand an accuracy of polarization measurement of Δ P/P < 1%. To ensure beam polarization, a polarimetry chain with polarimeters at different energies and working principles is planned to track the electron beam polarization throughout the MESA lattice. As a part of the chain, a Mott polarimeter will be installed after the pre-acceleration of the polarized beam to 5 MeV energy. Based on extensive background simulations, the design of vacuum system and target assembly has reached its final stage. A preliminary approach towards a detection system will also be presented.

Speaker: Rakshya Thapa (Johannes Gutenberg University of Mainz)

rhtapa_SPIN2023.pdf

151 Compton transmission polarimetry of laser-plasma accelerated electron beams

Polarised particle beams are indispensable for the study of spin-dependent processes. The LEAP (Laser Electron Acceleration with Polarisation) project at DESY aims to demonstrate the acceleration of polarised electrons in the extremely high fields enabled by laser plasma accelerators to create high energy electron beams in ultra-compact footprint. In this proof of principle experiment, spin-polarised electron beams with energies of tens of MeV will be generated in a submillimetre long plasma source. For electron beams of such energies, Compton transmission polarimetry is the ideal method to measure the polarisation. Gamma rays produced by bremsstrahlung are transmitted through an iron absorber core magnetised by a surrounding solenoid, with rate and energy spectrum depending on the relative orientation of the gamma spin and the magnetisation direction of the iron. The transmission asymmetry with respect to the direction of the magnetisation is proportional to the initial electron polarisation.
In this contribution, an overview of the LEAP project is presented, detailing the setup of the polarimeter as well as its implementation and commissioning status.

Speaker: Jennifer Popp (Deutsches Elektronen-Synchrotron DESY)

jp_SPIN2023_final.pdf

Application of Nuclear Polarization Techniques to Other Fields: Application III

152 Singlet and Zeeman Relaxation Mechanisms Studied by Experiment and Computation

Over the years, several relaxation mechanisms have been identified, including dipolar coupling, chemical shift anisotropy, paramagnetic relaxation, spin rotation and spin-internal motion, and the scalar relaxation of the second kind. While in principle, many of the mechanisms are well understood, estimating their size can be difficult. Furthermore, multiple experimental examples have been found that decidedly defy expectations.

We present here work on directly estimating singlet relaxation mechanisms from molecular dynamics simulations. Nuclear spins states have been shown to exceed spin-lattice relaxation times several fold, with impressive demonstrations of singlet lifetimes of more than an hour in organic molecules in solution. Here we show calculations for intermolecular mechanisms and find good agreement with experiment. It is particularly surprising to see that such mechanisms as intermolecular coupling to 35Cl and 37Cl nuclear spins (of the chloroform solvent) could be rate limiting for singlet states.
In addition, the spin-rotation relaxation mechanism is shown to be pronounced for both singlet and Zeeman order. Good agreement between experiment and computation is achieved. Furthermore, we discuss the importance of taking into account internal motion when calculating spin-rotation tensors.

Calculations of this sort may help in the design of particularly long-lived singlet states, or could be used to identify new probes for dynamics.

Speaker: Prof. Alexej Jerschow (New York University)

153 Expanding hyperpolarization target scope with new approaches to spin polarization transfer

The hyperpolarization technique Signal Amplification By Reversible Exchange (SABRE) distills spin polarization from parahydrogen during reversible chemical interactions of the target with a catalyst. Typically, the largest spin polarization can be generated at ultralow magnetic fields (B~10 μT). At these fields, roughly 5% spin polarization may be generated on nuclear targets like $^{13}C$ and $^{15}N$ in seconds, with hundreds of molecular targets demonstrated. However, the ultralow field conditions often permit polarization flow out of the target nucleus into auxiliary nuclei. For instance, hyperpolarization in the presence of a spin-1 quadrupolar nucleus at ultralow field is not possible with the current array of techniques, as polarization flow to the quickly relaxing quadrupolar nucleus quenches the available spin polarization. Here, we will discuss the development of two new spin polarization methods that circumvent such issues by utilizing shaped magnetic fields (trivial to implement) and field sequences. The first approach focuses on the polarization of $^{13}C$ (spin-1/2) in the presence of a $^{14}N$ (spin-1) nucleus. The second builds in methods to prevent polarization from flowing to other spin-1/2 nuclei throughout the experiment. These new experimental methods offer a way to expand the scope of hyperpolarizable targets and improve the efficiency of the polarization process.

Speaker: Dr Jacob Lindale (Duke University)

154 Improving Spin Hyperpolarization with SABRE using multiaxial ZULF sequences

Signal Amplification By Reversible Exchange (SABRE) is a hyperpolarization method that generates large, non-equilibrium spin polarizations by transferring spin order from parahydrogen ($|S_H ⟩$) to magnetized states on a target nucleus ($|α_L ⟩$). An iridium-based catalyst simultaneously and reversibly binds parahydrogen and a target ligand with spin-1/2 nuclear target(s) L. Under the right field conditions, couplings then facilitate flow of spin order out of an initially overpopulated singlet hydrogen state into ligand polarization. The most common initial SABRE approach uses low fields, which match energy separations to transfer magnetization at an avoided crossing. However, in the heteronuclear case, the optimal experimental continuous field is ≈-0.5 μT, while the avoided crossing matching condition is ≈-0.05 μT.
While this traditional framework can provide a general understanding of SABRE dynamics, our lab recently introduced several field sequences which never approach a matching condition instantaneously or on average, but still lead to an improvement in the polarization yield. This suggests that an additional degree of freedom, unique to low field experiments might be valuable: the ability to rapidly and fully manipulate fields in three dimensions. However, theoretical assessment is challenging because many terms in the Hamiltonian are comparably sized, and off-diagonal elements are on the same order as the difference in the energy levels. This is particularly confounding in SABRE, where chemical exchange rates are also comparable to J couplings and resonance frequency differences.
We report here two different multiaxial pulse sequence approaches, which improve SABRE spin population transfer to magnetized and singlet spin states. The first approach uses simple circularly polarized transverse irradiation at a field strength equivalent to the leading field to enhance polarization transfer. The second approach, Multi Axis Computer-aided HEteronuclear Transfer Enhancement (MACHETE) moved away from assuming a traditional pulse sequence structure and uses an evolutionary strategy to optimize the pulse shape in three-dimensions. This strategy has yielded a pulse sequence that shows a 7.5-fold experimental improvement in the polarization yield under SABRE hyperpolarization. This gain is highly nonintuitive as transverse fields do not inherently preserve longitudinal magnetization, but it is robust to a wide range of exchange rates and SABRE complex geometries. An average Hamiltonian approach turns out to be insightful. The eigenvectors of the average Hamiltonian show isolation of states such as $|S_H β_L ⟩$ and protection of magnetization on the unbound ligand, but substantial mixing of the $|S_H α_L ⟩$ spin state with states such as $|T_H^+ β_L ⟩$, thus building up spin-down magnetization on the ligand(s). These waveforms, compatible with any 3-channel AWG and a simple multiaxial electromagnet array provide a new strategy for understanding polarization transfer and optimizing population transfer into both magnetized and singlet states.

Speaker: Shannon Eriksson (Duke University)

Future Facilities and Experiments: Future II

Convener: Patrizia ROSSI (JEFFERSON LAB)

155 Physics with a Positron Beam at Jefferson Lab

Positron scattering from hadronic targets can provide new information that cannot be accessed with electron scattering alone. The asymmetry in deeply virtual Compton scattering cross sections between positrons and electrons can provide a critical handle on the Bethe-Heitler background process. A similar asymmetry in elastic scattering can reveal the contribution from two-photon exchange, which has been suggested as a possible explanation for the puzzling discrepancy in measurements of the proton's form factors at high momentum transfer. Positron capture and annihilation offer new ways to measure axial form factors, search for light dark matter, and probe fundamental symmetries. For these reasons, the Jefferson Lab Positron Working Group is working to bring positron capabilities to Jefferson Lab. In this talk, I will present the design concept for producing and injecting polarized positrons into CEBAF, and review the range of experiments that would be made possible with positrons at Jefferson Lab.

Speaker: Axel Schmidt (George Washington University)

20230925_schmidt_spin.pdf

156 A positron beam at CEBAF

Positron beams are considered as a new capability for the CEBAF 12 GeV accelerator at Jefferson Lab. This capability would provide a unique facility for hadronic physics experiments and tests of the Standard Model. Secondary e+/e- particle beams are created using the polarized bremsstrahlung of an intense continuous-wave (CW) spin polarized primary electron beam. To do this, the existing Low Energy Research Facility is re-imagined with a new 300 kV dc HV GaAs photogun which provides an intense ~1 mA and highly polarized ~90% electron beam. This beam is accelerated to ~100 kW and directed to a rotating W-target, where secondary e+ (or e-) are collected to a CW beam, accelerated to 123 MeV and injected to CEBAF for energies up to 12 GeV. This new Ce+BAF configuration is optimized to provide experiments with positron spin polarization >60% and intensity greater than >50 nA, and greater intensities when high spin polarization is not required.

Speaker: Joe Grames (JLab)

SPIN23-Grames-FINAL.pptx

157 22 GeV CEBAF with Novel FFA Design

Extending CEBAF energy reach by increasing the number of recirculations, while using the existing SRF system is being explored. Proposed energy upgrade is based on a new approach to multi-pass acceleration of electrons in a single Fixed Field Alternating Gradient (FFA) beam line, configured with Halbach-style permanent magnets. Encouraged by recent success of CBETA, a proposal was formulated to nearly ‘double’ CEBAF energy by replacing the highest energy arcs with a pair of FFA arcs. The new non-scaling FFA arcs would support simultaneous transport of additional 6 passes with energies spanning a factor of two. One of the challenges of the multi-pass (11) linac optics is to assure uniform focusing in a vast range of energies, in a fixed field lattice. Here, we propose a triplet lattice that would provide a stable periodic solution covering energy ratio of 1:33. The current CEBAF injection at 123 MeV, makes optical matching in the first linac virtually impossible due to extremely high energy span ratio (1:175). Replacement of the current injector with a 650 MeV recirculating injector will alleviate that problem. Orbital and optical matching from the FFA arcs to the linacs is implemented as a compact non-adiabatic insert. Presented scheme would promise to deliver a 22 GeV beam with normalized emittance of 80 mm·mrad and with a relative energy spread of 1.5×10-3. Further recirculation beyond 22 GeV is limited by large, 974 MeV per electron, energy loss due to synchrotron radiation.

Speaker: Dr Alex Bogacz (Jefferson Lab)

SPIN_2023_Bogacz.pptx

158 Future studies of dihadron production in SIDIS

Spin asymmetry and cross section measurements in semi-inclusive hadroproduction grant access to a variety of parton distribution and fragmentation functions. Such measurements of dihadron production additionally constrain Dihadron Fragmentation Functions (DiFFs), and the extra degree of freedom from the second hadron facilitates access to some of the parton distribution functions. At CLAS kinematics, subleading-twist parton distributions are accessible in dihadron beam-spin and target-spin asymmetries, and a comparison of semi-inclusive scattering off a proton and a deuteron probes their flavor dependence. The future Electron-Ion Collider (EIC) with a transversely polarized proton will access several transverse-momentum dependent distributions such as Sivers and transversity. On the fragmentation side, numerous DiFFs are accessible, and their partial wave expansion probes correlations between the angular momentum of the fragmenting parton with that of the observed dihadron. Furthermore, different hadron channels probe flavor dependence in fragmentation. Together with CLAS, the EIC as well as CLAS with the proposed 22 GeV accelerator upgrade will cover a broad range of $Q^2$ and $x$, allowing for the study of evolution effects of all of these functions. This presentation will summarize the possibilities of these measurements at CLAS and at future experimental facilities.

Speaker: Christopher Dilks (Jefferson Lab)

dilks_SPIN2023.pdf

Nucleon Helicity Structure: Helicity VI

Convener: Sebastian Kuhn (Old Dominion University)

159 Analytic Solution for the Revised Helicity Evolution at Small $x$ and Large $N_c$: New Resummed Gluon-Gluon Polarized Anomalous Dimension and Intercept

We construct an exact analytic solution of the revised small-$x$ helicity evolution equations derived previously. The equations we solve are obtained in the large-$N_c$ limit (with $N_c$ the number of quark colors) and are double-logarithmic (summing powers of $\alpha_s \ln^2(1/x)$ with $\alpha_s$ the strong coupling constant and $x$ the Bjorken $x$ variable). Our solution provides small-$x$, large-$N_c$ expressions for the flavor-singlet quark and gluon helicity parton distribution functions (PDFs) and for the $g_1$ structure function, with their leading small-$x$ asymptotics given by
\begin{align}
\Delta \Sigma (x, Q^2) \sim \Delta G (x, Q^2)
\sim g_1 (x, Q^2) \sim \left( \frac{1}{x} \right)^{\alpha_h} , \notag
\end{align}
where the exact analytic expression we obtain for the intercept $\alpha_h$ can be approximated by $\alpha_h = 3.66074 \, \sqrt{\frac{\alpha_s \, N_c}{2 \pi}}$. Our solution also yields an all-order (in $\alpha_s$) resummed small-$x$ anomalous dimension $\Delta \gamma_{GG} (\omega)$ which agrees with all the existing fixed-order calculations (to three loops). Notably, our anomalous dimension is different from that obtained in the infrared evolution equation framework developed earlier by Bartels, Ermolaev, and Ryskin (BER), with the disagreement starting at four loops. Despite the previously reported agreement at two decimal points based on the numerical solution of the same equations, the intercept of our large-$N_c$ helicity evolution and that of BER disagree beyond that precision, with the BER intercept at large $N_c$ given by a different analytic expression from ours with the numerical value of $\alpha_h^{BER} = 3.66394 \, \sqrt{\frac{\alpha_s \, N_c}{2 \pi}}$. We speculate on the origin of this disagreement.

Speaker: Jeremy Borden (The Ohio State University)

Spin2023borden.pdf

160 Orbital Angular Momentum at Small-x Revisited

We revisit the problem of the small Bjorken-$x$ asymptotics of the quark and gluon orbital angular momentum (OAM) distributions in the proton utilizing the revised formalism for small-$x$ helicity evolution derived recently in [1]. We relate the quark and gluon OAM distributions at small $x$ to the polarized dipole amplitudes and their (first) impact-parameter moments. To obtain the $x$-dependence of the OAM distributions, we derive novel small-$x$ evolution equations for the impact-parameter moments of the polarized dipole amplitudes in the double-logarithmic approximation (summing powers of $\alpha_s \ln^2(1/x)$ with $\alpha_s$ the strong coupling constant). We solve these evolution equations numerically and extract the large-$N_c$, small-$x$ asymptotics of the quark and gluon OAM distributions, which we determine to be
\begin{align}
L_{q+\bar{q}}(x, Q^2) \sim L_{G}(x,Q^2) \sim \Delta \Sigma(x, Q^2) \sim \Delta G(x,Q^2) \sim \left(\frac{1}{x}\right)^{3.66 \, \sqrt{\frac{\alpha_s N_c}{2\pi}}},
\end{align}
in agreement with [2] within the precision of our numerical evaluation (here $N_c$ is the number of quark colors). We also investigate the ratios of the quark and gluon OAM distributions to their helicity distribution counterparts in the small-$x$ region.

[1] F. Cougoulic, Y.V. Kovchegov, A. Tarasov and Y. Tawabutr, Quark and gluon helicity evolution at small x: revised and updated, Journal of High Energy Physics 2022 (2022).
[2] R. Boussarie, Y. Hatta and F. Yuan, Proton Spin Structure at Small-x, Phys. Lett. B797 (2019) 134817 [1904.02693].

Speaker: Brandon Manley (Ohio State University)

ManleySPIN23.pdf

161 Extraction of the strong coupling with HERA and EIC inclusive data

The sensitivity to the strong coupling $\alpha_S(M^2_Z)$ is investigated using existing Deep Inelastic Scattering data from HERA in combination with projected future measurements from the Electron Ion Collider (EIC) in a next-to-next-to-leading order QCD analysis. A potentially world-leading level of precision is achievable when combining simulated inclusive neutral current EIC data with inclusive charged and neutral current measurements from HERA, with or without the addition of HERA inclusive jet and dijet data. The result can be obtained with significantly less than one year of projected EIC data at the lower end of the EIC centre-of-mass energy range. Further improvements in the determination based on jets and nucleon's spin structure are being considered as are some unresolved questions over the uncertainties due to missing higher orders in the theoretical framework.

Speaker: Zuhal Seyma Demiroglu (CFNS, Stony Brook University)

HERA_EIC_alpha_s_SPIN2023_ZSDemiroglu.pdf

Polarized Ion and Lepton Sources and Targets: Sources and Targets VI

Convener: James Maxwell (JLab)

162 High precision magnetic compass

We have developed a novel type of magnetic compass based on a spinning Hall probe. It is used for determination of the magnetic field direction in the polarized He-3 target during the GEn experiment. This compass does not require prior calibration and has no problem with probe signal drift. Obtained accuracy is better than one milli radian. The compass concept and design will be presented.

Speaker: Bogdan Wojtsekhowski (Jefferson Lab)

Compass-BW.pdf

163 Every polarized neutron beam wishes it had a polarized target: a history of Polarized Nuclear Targets at the Triangle Universities Nuclear Laboratory

In 1984, when the Triangle Universities Nuclear Laboratory was building a polarized ion source there was an effort to build new cryogenic nuclear targets that could be used for measurements of neutron-nucleus spin interactions and later, searches for parity and time reversal violation in the neutron-nucleus interaction. The initial statically polarized targets were cooled to near 10 mK in a 7 T magnetic field. A second target cooled a single crystal of Holmium which could be rotated at low temperature in a test of time-reversal violation. A third, dynamically polarized, target cryostat was used to study the n-d and n-p interactions. This research group also contributed to two significant neutron experiments at Los Alamos National Laboratory. This program produced over 30 papers, 5 Ph.D.'s, 4 postdocs and one American Physical Society graduate student research award.

Speaker: Dr David G. Haase (NC State University)

164 Improved 3He Targets for the A1n and GEn Experiments at JLab

Recent experiments at Jefferson National Laboratory (JLab) utilize polarized $^3$He targets at high luminosity to study the structure functions and elastic form factors of the neutron. One experiment explores the spin asymmetry in the virtual photoabsorption cross section on the neutron, $A_1^n$. This experiment ran at JLab early to mid 2020. The other experiment explores the neutron electric form factor $G_E^n$ and will complete data taking during September of this year.

The design, construction, and characterization of these polarized $^3$He targets has evolved rapidly from $A_1^n$ to $G_E^n$. In this talk, I’ll discuss the hurdles we faced creating larger $^3$He targets as well the improvements we’ve made to the targets, allowing us to increase luminosity by a factor of three between these experiments.

Speaker: Christopher Jantzi (University of Virginia)

SPIN 2023 - Jantzi.pdf

SPIN 2023 - Jantzi.pptx

Spin physics in Nuclear Reactions and Nuclei: Nuclear IV

Convener: Elena Long (University of New Hampshire)

165 Covariant framework to parametrize realistic deuteron wave functions

As the simplest nucleus, the generalized parton distributions of the deuteron are highly desirable. These should be calculated in a manifestly covariant manner in order to ensure polynomiality, which is needed to allow extraction of the energy-momentum tensor. However, the Bethe-Salpeter equation is notoriously difficult to solve, with approximations usually breaking covariance. Thus, as an alternative to the usual approaches, a separable approximation of the nucleon-nucleon interaction kernel can be used, which is manifestly covariant but non-local. I will describe how a relativistic separable interaction can be constructed in such a way to reproduce existing precision wave functions in the non-relativistic limit, and present preliminary results for the electromagnetic form factors and collinear parton distributions of the deuteron in this framework.

Speaker: Adam Freese (Jefferson Lab)

Freese_Slideshow.pdf

166 Spin Physics at Nuclotron: Status and Perspectives

Recent results on the spin effects in deuteron-proton elastic scattering, beam and focal polarimetry using polarized deuteron and proton beams from new polarized ion source at Nuclotron-JINR facility are discussed. The vector Ay and tensor Ayy and Axx analyzing powers in deuteron-proton elastic scattering at large transverse momenta obtained at internal target at Nuclotron in the energy range 400-1800 MeV are obtained. These data on the deuteron analyzing powers in the wide energy range demonstrate the sensitivity to the short-range spin structure of the isoscalar nucleon-nucleon correlations.
The perspectives of further progress in physics program as well as in the development of the polarimetry and proton spin manipulation techniques are disscussed.

Speaker: Dr Vladimir Ladygin (VBLHEP JINR)

VLadygin_DSS_SPIN2023v3.pdf

167 Polarized Target Nuclear Magnetic Resonance Measurements with Deep Learning

Constant current continuous wave Nuclear Magnetic Resonance (NMR) has been an essential tool for solid-state polarized target experiments in Nuclear and High-energy physics. Q-meter based phase-sensitive detection can provide accurate monitoring of the polarization over the course of a scattering experiment but is frequently limited by significant noise and systematic errors that arise during the data taking. In this talk, we present recent studies of improved signal-to-noise in NMR-based polarization measurements as well as reliable measurements outside of the originally designated range of the Q-meter’s operational parameters with the use of machine learning (ML). This approach will provide improved real-time online polarization monitoring and offline polarization data analysis for an increased overall figure of merit in the scattering experiments.

Speaker: Devin Seay (University of Virginia)

168 Neutron spin study using CLAS12 and polarized 3He target at JLab

Understanding the origin of the spin of nucleons is an overarching challenge for nuclear physics research. The spin structure information of proton and neutron are both crucial for flavor separation study but there are a very limited number of neutron spin measurements due to the lack of a free neutron target. Therefore, Polarized 3He has been used as an effective neutron target for neutron spin study. A comprehensive neutron spin physics program using CLAS12 and a polarized 3He target at JLab will be presented in this talk. While the DIS and semi-DIS measurements will provide access to study flavor dependence of the quark polarization determining their transverse momentum dependence. The Quasi-elastic measurement will provide information on the ground states of 3He which will help to suppress the largest systematic uncertainty from the spin structure function extraction to obtain high precision measurements.

Speaker: Dien Nguyen (JLAB)

Spin2023_Dien.pdf

169 ISPC Meeting

7:00 PM ISPC Dinner

Wednesday, September 27

3D Structure of the Nucleon: GPDs and Form Factors: GPDs IV

Convener: Paweł Sznajder (National Centre for Nuclear Research)

170 Observables for electro-scattering on targets with arbitrary spin

Starting from the Weinberg formalism for the construction of fields for arbitrary spin, we propose an algorithm for the construction of the independent operators that enter the scattering amplitude associated with electromagnetic observables. This procedure is advantageous for the systematic study of the structure of hadrons and nuclei, particularly in the case of spin-dependent observables. As higher spin targets exhibit new features in their hadronic structure, the investigation of these properties can enhance our understanding of the strong force. To demonstrate the efficacy of this method, we apply it to the description of elastic electroscattering on a spin 1 target, such as the deuteron. The results of calculations within Instant and Light-Front forms of dynamics are presented, together with a systematic identification of the electromagnetic form factors and potential extensions of the formalism to hard exclusive processes on the deuteron.

Speaker: Frank Vera (Florida International University)

F_Vera_Spin2023.pdf

171 Measurement of the Neutron Electromagnetic Form Factor Ratio GEn/GMn at High Q^2

Nucleon elastic form factors encode crucial information about its charge and magnetization distributions. For many decades, nucleon form factors were studied by using unpolarized electron-nucleon cross section measurements. The advent of electron beams with higher luminosities and beam polarization coupled with large acceptance detectors, polarized targets and recoil polarimeters enabled a wealth of information on nucleon form factors over a broad range of momentum transfer ($Q^2$). While plenty of information is available on the proton, no data above $Q^2$ = 3.5 GeV$^2$ is available on the neutron electric form factor. Pushing the data to a higher $Q^2$ allows constraining spin flip GPDs and serves as a benchmark for various theoretical models. Using quasi-elastic scattering of a polarized electron beam on a polarized $^3$He target, one can extract the $G_E^n$ term which is proportional to the measured asymmetry from opposite electron beam helicity.
The goal of the SBS (Super Bigbite Spectrometer) physics program in Hall A at Jefferson Lab is to conduct a series of experiments to measure the electric and magnetic form factors of the proton and the neutron at an unprecedentedly high $Q^2$. One of the experiments, GEn-II (E12-09-016) is aimed at measuring the neutron electric form factor using the double-polarization technique with both a polarized electron beam and a polarized $^3$He target. This experiment finished taking data at three out of four kinematic settings and is scheduled for completion in the Fall of this year. The physics motivation and status of the experiment will be discussed in this talk. This work was supported in part by DOE grant DE-FG02-96ER41003.

Speaker: Todd Averett (William & Mary)

SPIN2023_GEn_talk.pdf

172 Measuring the electric form factor of the proton up to Q^2 of 12~GeV^2 in Hall A at Jefferson Lab

Measurements of the elastic electromagnetic form factors of the proton and neutron have been a central component of Jefferson Lab’s scientific program for almost four decades and have been important, among other things, in constraining Generalized Parton Distributions and testing the validity of the onset of perturbative quantum chromodynamics. The ratio of $G_E^p/G_M^p$ measured in the late 1990s at Jefferson Lab via the polarization transfer technique and published in 2000 showed that $G_E^p$ falls off more rapidly than $G_M^p$ at $Q^2>1$ GeV$^2$ in contradiction of results from cross section measurements using the Rosenbluth separation method. This led to the measurement of $G_E^p/G_M^p$ by the recoil poalrization method up to 8.5~GeV$^2$ in 2008. A new measurement of $G_E^p$ is under preparation with plans to reach as high as 12 GeV$^2$. With the form factor dropping as $Q^{-4}$ and the cross section as $Q^{-12}$, going to high $Q^2$ is a challenge, with a large acceptance needed for statistics and the ability to discriminate elastic events from the backgrounds at very high background rates. I will discuss the motivation for this new measurement and how some of the challenges will be met.

Speaker: Donald Jones Jones (Temple University)

GEp5_SPIN2023.pptx

173 Measurement of the weak neutral current form factor of the proton at high momentum transfer

The elastic form factors of the proton and neutron are fundamental observables representing a projection of the internal structure of the nucleon. Measurements of the electromagnetic form factors of the proton and neutron can be combined to separately determine contributions from the $u$ and $d$ constituents of the nucleon, however, this interpretation relies on assumptions of both charge symmetry and negligible contributions from strangeness form factors. These assumptions are virtually untested at high momentum transfer, introducing a large uncertainty in flavor-separated form factors. The COIN proposal at Jefferson Lab aims to measure parity-violation with coincidence detection of electron-proton elastic scattering at $Q^2 = 2.5~\mbox{GeV/c}^2$, to determine the weak form factor of the proton. This will provide a crucial check of these assumptions which will greatly improve the precision of the flavor-separated electromagnetic nucleon form factors.

Speaker: Kent Paschke (UVA)

Paschke_ProtonWeakFormFactor_SPIN23.pdf

Paschke_ProtonWeakFormFactor_SPIN23.pdf

3D Structure of the Nucleon: TMDs: TMDs VII

Convener: Tommaso Rainaldi (Old Dominion University)

174 New measurements of transverse spin asymmetries at COMPASS

The COMPASS experiment has taken data from 2002 to 2022, at the CERN SPS. A consistent part of the data taking has been dedicated to SIDIS measurements with 160 GeV muon beam and longitudinally and transversely polarized targets. In these years many results have been produced, in particular for transverse spin asymmetries, and have been used for extractions of the transversity and the Sivers functions. For this phenomenological work, it turned out clearly that the statistics of the existing deuteron and neutron data were too scarce and that more data were needed. For this reason, COMPASS dedicated the last year of data taking to SIDIS off transversely polarized deuteron. The data taking was successful, and the data analysis is going on at high speed. Many measurements are expected from this data, and first results will be shown here.

Speaker: Anna Martin (Trieste University &amp; INFN)

martin_spin2023_a.pdf

175 Angular distribution measurements in the Drell-Yan process at the SeaQuest experiment

Over the last few decades, three-dimensional imaging of the nucleon, such as the transverse momentum dependent parton distribution functions (TMDs), has received much attention to better understand the structure of the nucleon. The Boer-Mulders function is one of the TMDs that represents the correlation between the transverse spin and the transverse momentum of the quark. It is suggested that the Boer-Mulders function leads to a cos2ϕ modulation in the azimuthal angular distribution of the pion induced Drell-Yan process. This suggestion was later found to be consistent with the fixed-target Drell-Yan experiment E866 using the 800 GeV proton beam from the Fermilab Main Injector. Now the azimuthal angular distributions of leptons in the Drell-Yan process are regarded as an important tool for accessing TMDs.
Compared to the E866 results, SeaQuest will extend the angular distribution to a larger x region using the 120 GeV proton beam on a LH2 target. In this talk, we will report the preliminary SeaQuest results of ν with 40% of the full SeaQuest data collected.

Speaker: Zhaohuizi Ji

Spin2023_0927-ZhaohuiziJi.pdf

176 The Sivers asymmetry of vector meson production in semi-inclusive deep inelastic scattering

The transverse single spin asymmetries of $\rho^0$ production in semi-inclusive deep inelastic scattering (SIDIS) are recently measured by COMPASS. Among them, the Sivers asymmetry can be described by the convolution of the Sivers function and unpolarized fragmentation function within the transverse momentum dependent (TMD) factorization. We perform a phenomenological study and find that the COMPASS data can be well described by the nucleon Sivers functions extracted from previous SIDIS data with pion and kaon productions. Therefore, it provides a universality test of the nucleon Sivers functions within the current experimental precision. Based on the result, we predict the Sivers asymmetry of $\rho^0$ production in SIDIS at future experimental facilities, such as the electron-ion colliders. The production of other vector mesons, like $K^*$, is also discussed.

Speaker: Yongjie Deng (Institute of Frontier and Interdisciplinary Science, Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University)

SPIN2023.pdf

177 An extraction of the Sivers, and the Boer-Mulders functions in SU(3) with DNNs

Transverse Momentum Dependent Parton Distribution Functions (TMDPDFs) can be extracted from the processes that are corresponding to multiple kinematic scales such as Drell-Yan (DY), Semi Inclusive Deep Inelastic Scattering (SIDIS), and $e^+$ $e^-$ annihilation. Among the eight leading-twist TMDPDFs, there are two time-reversal odd TMDs, namely the Sivers function and the Boer-Mulders function, which represent the correlation between the spin of the quark and the spin of the hadron. These T-odd TMD PDFs have connections to the partons' orbital angular momenta contributing to the overall angular momentum of the hadron. Deep Neural Networks (DNNs) are quickly becoming an invaluable tool for information extraction and modeling. DNN models can be built and trained to make predictions of the Transverse Momentum-dependent Distributions (TMDs) based on fits to Semi Inclusive Deep Inelastic Scattering (SIDIS) and Drell-Yan (DY) data. An analysis of the Sivers, and the Boer-Mulders functions in $SU(3)_{flavor}$ using DNNs with available experimental data as well as utilizing the transverse momentum of di-muons' ($q_T$) dependence of the measured DY asymmetries from DNN-based reconstruction techniques will be presented in this talk.

Speaker: Ishara Fernando (University of Virginia)

SPIN2023_Sivers_BM_IsharaFernando.pdf

178 Deep Neural Network-Based Reconstruction to extract unpolarized Drell-Yan Asymmetries and the Boer-Mulders Function from SeaQuest E906 Data

The Boer-Mulders function is a transverse momentum distribution that describes the net polarization of partons within an unpolarized nucleon. A non-zero Boer-Mulders function suggests a handedness of the nucleon and gives rise to a measurable azimuthal asymmetry in Drell-Yan scattering. We suggest a novel approach utilizing DNN-based reconstruction techniques to extract unpolarized Drell-Yan asymmetries from SeaQuest E906 data, which can be used to extract the Boer-Mulders function. This reconstruction technique could be significantly faster than existing methods, potentially allowing us to lower statistical error on the angular-dependence coefficients $\lambda$, $\mu$, and $\nu$. With lower statistical error, we can calculate the value of these constants in more bins, allowing for more general extraction of the Boer-Mulders function, which is highly sensitive to the $p_T$ dependence of $\nu$. SeaQuest at Fermilab was a fixed-target experiment designed to detect the Drell-Yan process in $p+p$ and $p+d$ reactions. We discuss the steps involved in our DNN reconstruction process, including data preprocessing, network architecture design, and training strategies, while addressing challenges such as background estimation, and systematic uncertainties.

Speaker: Arthur Conover (University of Virginia)

Spin2023_Talk_Conover.pdf

Fundamental Symmetries and Spin Physics Beyond the Standard Model: Fundamental Symmetries IV

179 High Precision Parity Experiments as a Probe for new Physics and Benchmark Measurements

The phenomenon of parity violation in the Weak interaction has been used to study the fundamental interactions between the constituents of matter since its discovery, at ever increasing levels of precision. This need for precision has driven the evolution of experimental techniques to such an extent that parity experiments can now be used to investigate interactions at the smallest scales in the electro-weak sector. Or, on the other hand, provide highly precise benchmark measurements in areas that are plagued with theoretical difficulties, such as the strong interaction sector in the non-perturbative regime at low energy. In this talk I will discuss a few (certainly non-exhaustive) examples of experiments from electron scattering and neutron physics. I will describe some common techniques and the general ways in which they are used in both areas to push experimental precision.

Speaker: Prof. Michael Gericke (University of Manitoba)

PVPrecisionExp.pdf

9:25 AM Discussion

180 Update of the muon g-2 measurement at Fermilab

The well-known Dirac's relativistic quantum mechanics prediction of $g=2$ for the magnetic dipole moment of a point particle, e.g., an electron, breaks down at the $10^{-3}$ level. The resulting magnetic anomaly, $a_e = (g − 2)/2$, is due to couplings to virtual particles excited in the vacuum. Due to its greater mass, the muon probes significantly deeper into the high-mass excitations of the vacuum than does the better studied electron. For this reason, the efforts to measure the muon magnetic anomaly, $a_\mu$, have persisted over decades. The most recent such effort to report results is Fermilab Muon $g-2$ experiment, E989.

E989 follows closely in the footsteps of its predecessor, the Brookaven National Lab E821, having transported the BNL 821 muon storage to a dedicated muon beam line at Fermilab, and implemented a number of critical improvements. In July 2023 E989 concluded data taking in its last run cycle, Run-6, and a month later unblinded and published analysis results of data from Runs 2 and 3, that add to the Run 1 results published in 2021. The new results have brought about an improvement by a factor of two in the precision of the world average of $a_\mu$. In parallel, recent theoretical and experimental developments regarding the hadronic vacuum polarization (HV) have led to a reexamination of the context for the interpretation of the measured value of $a_\mu$.

This talk will examine the new results of Fermilab E989, discussing the experimental method and the resulting uncertainties. We will place the new result in the context of a changing HVP landscape, and will review the future plans for the field.

Speaker: Dinko Pocanic (University of Virginia)

muon_g-2_update-pocanic.pdf

9:50 AM Discussion

181 Toward testing the magnetic moment of the tau at one part per million

Speaker: Michael Roney (University of Victoria)

TauMagnetMomentChiralBelle-SPIN2023June20.pdf

10:15 AM Discussion

182 Mu2e: Probing the Frontiers of Physics Using Muons

The absence of any signature for new physics beyond the standard model at
the Large Hadron Collider has left the field of elementary particle physics in a quandary. We know there is new physics out there: where best to look for it? Searches for certain rare processes provide ultra-sensitive probes for new physics and can reach mass scales unobtainable by any conceivable accelerator, present or imagined. We describe an experiment, Mu2e, that intends to use a novel technique to search for new physics through lepton flavor violation in muon decays with sensitivities a factor of 10,000 over existing limits.

Speaker: Edmond Dukes (University of Virginia)

mu2e_seminar_2023_09_spin.pptx

10:40 AM Discussion

Future Facilities and Experiments: Future III

183 SoLID: Investigating the Nucleon at Intensity Frontier

Solenoidal Large Intensity Detector (SoLID) is a large acceptance, high luminosity device proposed for exploiting the full potential of the Jefferson Lab (JLab) 12 GeV energy upgrade. The scientific program of SoLID includes six approved experiments: three Semi-Inclusive Deep Inelastic Scattering (SIDIS), two Parity-Violating Deep Inelastic Scattering (PVDIS), and one $J/\psi$ production. As a large acceptance detector capable of operating in an extremely high luminosity environment ($10^{37\rm{-}39}$/cm$^2$/s), SoLID provides a unique opportunity to achieve various scientific goals, including but not limited to the precision 4D mapping of the nucleon structure, probing physics beyond the Standard Model, and investigating the gluonic structure of the proton. After years of work by the SoLID collaboration, a robust, low risk and flexible design concept, which is capable of accomplishing this broad and vibrant physics program, was determined. Many key components of the detector were also demonstrated functional in the extremely high luminosity environment through the DOE-funded and JLab-supported pre-R\&D activities. This talk will give an overview of SoLID and its scientific program.

Speaker: Chao Peng (Argonne National Laboratory)

SPIN2023_SoLID_Chao.pdf

184 Parity Violation in DIS Region with SoLID at JLab 12 GeV

In this talk, we will provide an overview of future parity violation deep inelastic scattering (PVDIS) experiments by using the Solenoidal Large Intensity Device (SoLID) at Jefferson Lab (JLab) Hall A. We will obtain data with high statistic and large kinematic coverage for Bjorken $0.25

Speaker: Ye Tian (Syracuse University)

SPIN2023_PVDIS.pdf

185 The MOLLER Experiment: An Ultra-Precise Measurement of the Weak Mixing Angle Using Moller Scattering

The MOLLER (Measurement Of a Lepton Lepton Electroweak Reaction) experiment aims to measure the parity-violating asymmetry $A_{PV}$ in the scattering of longitudinally polarized electrons off unpolarized electrons with an uncertainty of 0.8 ppb. This measurement can be used to directly determine the weak mixing angle at low $Q^{2}$ with the best precision ($\delta(\sin^2\theta_W) = \pm 0.00028$) that matches $Z$-pole measurements. This precise $A_{PV}$ measurement will be sensitive to the interference of the electromagnetic amplitude with new neutral current amplitudes as weak as $10^{-3}$$\cdot$$G_{F}$ from as yet undiscovered dynamics beyond the Standard Model. The resulting discovery reach is unmatched by any proposed experiment measuring a flavor- and CP-conserving process at low energy over the next decade, and yields a unique window to new physics at MeV and multi-TeV scales, complementary to direct searches at high energy colliders such as the Large Hadron Collider (LHC). The experiment takes advantage of the unique opportunity provided by the upgraded electron beam energy, luminosity, and stability at Jefferson Laboratory and the extensive experience accumulated in the community after a round of recent successfully completed parity-violating electron scattering experiments. This talk will overview the physics motivation and the apparatus and report on the status and immediate plans of the MOLLER construction project.

Speaker: Zuhal Seyma Demiroglu (CFNS, Stony Brook University)

MOLLER_Spin2023_ZSDemiroglu.pdf

Joint Helicity/Nuclear: Joint Helicity/Nuclear I

Convener: Sebastian Kuhn (Old Dominion University)

186 Tensor polarized deuteron structure

Scattering reactions on the deuteron, being spin 1 and having tensor polarization modes, involve more independent structures than those on the nucleon. I discuss aspects of the tensor polarized asymmetry Azz in deep inelastic scattering on the deuteron. In light of the upcoming JLab measurements I focus on and discuss the contributions of leading and higher-twist contributions to the asymmetry. I also demonstrate how tagging a spectator nucleon allows to measure maximal Azz (1,-2) asymmetries and provides constraints on the deuteron nuclear structure, in contrast to the inclusive values which are tiny. These measurements would be possible with the far-forward detecors at the EIC when operating with polarized deuteron beams.

Speaker: Wim Cosyn (Florida International University)

Cosyn_Spin_tensord.pdf

187 Tensor Polarized ND3 Target for Measuring Spin-1 Structure Functions

Several experiments are planned at Jefferson Lab and other facilities which will utilize a solid tensor polarized target. This new program will help clarify how the properties of the nucleus arise from the underlying partons, and provide novel information about gluon contributions, quark angular momentum, and the polarization of the quark sea that is not accessible in spin-1/2 targets. We will discuss the status of the target and experiments.

Speaker: Karl Slifer (University of New Hampshire)

2023_slifer_spin_v2.pdf

188 The polarized EMC effect: Planned experiments

The exploration of medium modification of unpolarized structure functions in nuclei has been underway for several decades. The theoretical descriptions of this effect, known as the “EMC effect”, are numerous and there is currently no universal community consensus about its cause. In this talk I will discuss something new, the very first investigation into the modification of polarized structure functions in the nuclear medium. I will discuss an approved Jefferson Lab experiment to measure bound proton spin structure functions in the 7Li nucleus with an 11 GeV electron beam.

Speaker: Will Brooks (Universidad Técnica Federico Santa María)

Brooks-pEMC-SPIN2023_v1.pdf

Low Energy Spin Physics with Lepton, Photon and Hadron Probes: Low Energy VI

Convener: Michaela Thiel

189 Measurement of the Proton Polarizabilities at MAMI

A central problem of modern physics research is the solution to QCD in the non-perturbative regime. One method of testing QCD in this low-energy region is by measuring certain structure constants of hadrons -- called polarizabilities -- that show particular promise of allowing a direct connection to the underlying quark/gluon dynamics through comparison to modern QCD-inspired model calculations, and to solutions of QCD done computationally on the lattice. This talk will report on recent results on the proton electric and magnetic dipole polarizabilities from a measurement at the Institute for Nuclear Physics in Mainz, Germany.

Speaker: David Hornidge (Mount Allison University)

spin_230927.pdf

spin_230927.pdf

190 Nucleon Spin Sum Rules and Neutron Spin Polarizabilities at low $Q$

We will report on recently published experimental results on spin sum rules, and particularly on the generalized spin polarizabilities $\gamma_0^n(Q^2)$ and $\delta_{LT}^n(Q^2)$. The data were taken at Jefferson Lab in Hall A and B by experiments E97-110 and EG4, respectively. They covered the very low $Q^2$ domain, down to $Q^2 \sim 0.02$ GeV$^2$, where Chiral Effective Field Theory ($\chi$EFT) predictions should be valid. While some obervables agree with the state-of-the-art $\chi$EFT theoretical predictions, others are in tensions, including $\delta_{LT}^n(Q^2)$ for which $\chi$EFT prediction was expected to be robust. This suggests that $\chi$EFT does not yet consistently describe nucleon spin observables, even in the very low $Q^2$ domain covered by the experiments.

Speaker: Alexandre Deur (Jefferson Lab)

Spin23_Deur.pdf

191 Proton spin structure at long distances

We will report on recently published experimental results on the proton longitudinal spin structure at long distance. The inclusive data were taken with the Jefferson Lab CLAS spectrometer in Hall B by experiment EG4. They covered the very low $Q^2$ domain, down to $Q^2 = 0.012$ GeV$^2$, where Chiral Effective Field Theory ($\chi$EFT) is applicable, thereby providing a test of its predictions.

Speaker: Alexandre Deur (Thomas Jefferson National Accelerator Facility)

Spin23_Deur.pdf

10:45 AM Coffee Break

3D Structure of the Nucleon: GPDs and Form Factors: GPDs V

Convener: Yoshitaka Hatta (Brookhaven National Laboratory)

192 First lattice QCD exploration of chiral-even axial twist-3 GPDs of the proton

We present the first calculation of twist-3 axial quark GPDs of the proton using lattice QCD combined with the large momentum effective theory (LaMET) approach. We use one ensemble of twisted mass fermions with degenerate light quarks, a strange and a charm quark, at a single lattice spacing of 0.093 fm and a pion mass of 260 MeV. We employ three proton boosts up to 1.67 GeV to test the convergence of the LaMET expansion. The light-cone twist-3 GPDs are defined in the symmetric frame, at negative momentum transfers squared of 0.69, 1.38 and 2.76 GeV^2 and at zero skewness. We extract the leading combinations of twist-3 axial GPDs and twist-2 helicity GPDs and we isolate some of the twist-3 ones, confirming that one of them vanishes at zero skewness. We also perform several consistency checks, such as the local limit of the extracted GPDs and the Burkhardt-Cottingham-type and Efremov-Teryaev-Leader-type sum rules.

Speaker: Krzysztof Cichy (Adam Mickiewicz University)

cichy-SPIN2023.pdf

193 Moments of proton GPDs from the OPE of nonlocal quark bilinears up to NNLO

We present a lattice QCD determination of Mellin moments of unpolarized generalized parton distributions (GPDs) of the proton from an analysis of the quasi-GPD matrix elements within the short-distance factorization framework. We perform our calculation on an $N_f$=2+1+1 twisted mass fermions ensemble with a clover improvement at lattice spacing $a=0.093$ fm and a pion mass of $m_\pi=260$ MeV. Focusing on the zero-skewness case, the iso-vector and iso-scalar quasi GPDs are calculated from the $\gamma_0$ definition, as well as a recently proposed Lorentz-invariant definition. We utilize data on both symmetric and asymmetric kinematic frames, which allows us to obtain the Mellin moments for several values of the momentum transfer, $-t$, in the range 0.17 to $2.77~\rm{GeV}^2$. We use the ratio scheme with leading-twist factorization formula and perturbatively calculated matching coefficients up to the next-next-to-leading order (NNLO) to extract Mellin moments of GPDs. We estimated the moments of GPDs up to the fifth ones for the first time. The impact parameter space interpretation of the GPD moments is discussed, which provides insights into the spatial distribution of unpolarized quarks and their correlations in the transverse plane of an unpolarized or transversely polarized proton.

Speaker: Xiang Gao

GPD_XG_0927.pdf

194 Lattice QCD calculation of the pion generalized parton distributions (GPDs)

We present a Lattice QCD calculation of the generalized parton distributions (GPDs) for the pion. Focusing on the zero skewness, we obtain the matrix elements from both symmetric and asymmetric kinematic frames with the recently proposed Lorentz-invariant definition. The calculations are performed using a single ensemble of $N_f=2+1$ highly-improved staggered quarks with $m_\pi = 300$ MeV and a lattice spacing $a=0.04$ fm. We extract the first few Mellin moments of GPDs using the ratio-scheme renormalization with the short distance factorization (SDF). Additionally, we also use a hybrid-scheme renormalization with perturbative matching to obtain the light-cone GPDs.

Speaker: Qi Shi (Brookhaven Nation Laboratory)

SPIN23_QiShi.pdf

195 Meson and Baryon spin dependent GPDs via Quantum Computers

Testing detailed predictions of QCD and searching for phenomena at the LHC requires knowing spin dependent Parton Distribution Functions for quarks and gluons. For some observables Generalized or Transverse Momentum pdf’s are needed. Calculating these distributions from QCD, ab initio, is prohibitively resource intensive and depends on non-perturbative techniques. Quantum simulation on a quantum computer of quantum field theories offers a new way to investigate properties of the fundamental constituents of matter. We develop quantum simulation algorithms based on the light-front formulation of relativistic field theories, beginning with Yukawa theories in 1+1D and 2+1D. We compute pdf’s and GPD’s for a model of pion-like mesons and quark-diquark baryons.

Speaker: Carter Gustin (Tufts University)

Spin2023V2.pdf

3D Structure of the Nucleon: TMDs: TMDs VIII

Convener: Daniel Pitonyak (Lebanon Valley College)

196 Nuclear modified transverse momentum distribution functions

In this talk, I'll discuss recent progress in our understanding of cold nuclear modifications to transverse momentum distribution. I'll begin by dicussing recent extractions of these distributions from SIDIS and Drell-Yan experiments. In particular, I'll focus on the first simultaneous global QCD extraction of the transverse momentum dependent (TMD) parton distribution functions and the TMD fragmentation functions in nuclei. I'll then discuss efforts to measure these distributions using jet.

Speaker: Mishary Alrashed

spin.pdf

197 Drell-Yan cross-section measurement at COMPASS

The COMPASS collaboration at CERN performed measurements of the Drell-Yan process using a 190 GeV negative pion beam scattering off a NH3 target and nuclear aluminium and tungsten targets, in the years 2015 and 2018. We present the results of differential cross sections of the dimuon events with the invariant mass between 4.3 and 8.5 GeV/c² in the kinematic regions of x-Feynman from -0.2 to 0.9 and transverse momentum up to 3.6 GeV/c. The measured differential cross sections are compared with the next-to-next-leading order QCD calculations and a reasonable agreement is observed. Our results represent a valuable input for constraining the PDF and the TMD of the pion.

Speaker: Vincent Andrieux

Andrieux_SPIN20230927.pdf

198 Measurement of the transverse single spin asymmetry for forward neutron production in a wide transverse momentum range

In the high-energy polarized $p+p$ collisions, finite transverse single spin asymmetry for forward neutron production was first observed at the IP12 experiment at Relativistic Heavy Ion Collider and it has been described by an interference between $\pi$ (spin flip) and $a_1$ (spin non-flip) exchange. The $\pi$ and $a_1$ exchange model predicted the neutron asymmetry would increase in magnitude with transverse momentum ($p_{\scriptsize{\textrm{T}}}$) with little longitudinal momentum fraction ($x_{\scriptsize{\textrm{F}}}$) dependence in $p_{\scriptsize{\textrm{T}}} < 0.4$ GeV/$c$. Recently, the PHENIX collaboration precisely extracted the neutron asymmetry as functions of $x_{\scriptsize{\textrm{F}}}$ and $p_{\scriptsize{\textrm{T}}}$ at center of mass energy of $\sqrt{s} = 200$ GeV and showed the validity of the $\pi$ and $a_1$ exchange model in $p_{\scriptsize{\textrm{T}}} < 0.2$ GeV/$c$. In June 2017, the RHICf collaboration measured the neutron asymmetry in a wide $p_{\scriptsize{\textrm{T}}}$ range of $0 < p_{\scriptsize{\textrm{T}}} < 1$ GeV/$c$ at $\sqrt{s} = 510$ GeV by installing an electromagnetic calorimeter at the zero-degree area of the STAR experiment. Using the RHICf data, one can test the validity of the $\pi$ and $a_1$ exchange model in the higher $p_{\scriptsize{\textrm{T}}}$ region and also can study if there is any $\sqrt{s}$ dependence in the neutron asymmetry. We present the final result of the neutron asymmetry measured by the RHICf experiment. A theoretical trial to understand the RHICf result other than $\pi$ and $a_1$ exchange mechanism will also be discussed.

Speaker: Minho Kim (RIKEN)

SPIN2023.pdf

199 Studying the Lund Jet Plane at LHCb

The substructure of QCD jets has been the subject of intense investigation following the development of infrared and collinear safe clustering algorithms and observables. A particularly illuminating observable to study the radiation patterns of light and heavy partons is the Lund jet plane (LJP), a multidimensional imaging technique of jets. By reclustering jets using the Cambridge/Aachen algorithm, then declustering them following the hardest/heavy-flavor branch, we can construct a representation of the LJP. This talk presents a status update on the LJP for light-, charm-, and beauty-initiated jets at the LHCb experiment, a well-optimized forward detector for studying heavy flavor physics. We expect mass effects to be revealed in various regions of the LJP such as the leading particle effect and the dead-cone effect.

Speaker: Ibrahim Chahrour (University of Michigan)

Chahrour_SPIN2023_final.pdf

200 Production of spin-3/2 hadrons in $e^+e^-$ annihilation and SIDIS

We investigate the inclusive and semi-inclusive productions of spin-3/2 hadrons, such as $\Omega$, in unpolarized $e^+e^-$ annihilation and lepton-nucleon deep inelastic scattering. The quark transverse momentum dependent (TMD) fragmentation functions (FFs) to spin-3/2 hadrons are defined for the first time from the decomposition of the quark-quark correlator at leading twist, 14 of which are newly defined for rank-3 tensor polarized hadron states. We perform a leading order calculation of the differential cross sections. In the inclusive hadron production in $e^+ e^-$ annihilation, only two structure functions are found nonzero and none of the rank-3 tensor polarized FFs contributes. For two-hadron production, half of the 48 structure functions are found nonzero even if the spin of the second hadron is not analyzed, and ten of the rank-3 tensor polarized TMD FFs contribute. These newly defined FFs can be further applied in semi-inclusive deep inelastic scattering (SIDIS) processes for the study of nucleon structures. For completeness, we consider the situations where all particles are polarized in SIDIS. For the unpolarized lepton case, half of 192 structure functions are nonzero and 42 of rank-3 tensor polarized TMD FFs contribute. Furthermore, if we consider the polarized lepton, one-third of 96 structure functions are nonzero and 14 of the nonzero structure functions are for rank-3 tensor polarized hadron states.

Speaker: Jing Zhao

JingZhao_SPIN 2023.pdf

Acceleration, Storage and Polarimetry of Polarized Beams: Acceleration III

Convener: Vadim Ptitsyn (BNL)

201 Three dimensional beam injection scheme for the new muon g-2/EDM experiment at J-PARC

Status of newly planned J-PARC muon g-2/EDM experiment will be reported. This experiment differs greatly from the BNL-E821 and FNAL-E989 experiments, which use a muon of magic momentum (γ=29.3). Utilizing low emittance muon beam with momentum of γ=3, we store the beam in 3T superconductive solenoidal magnet with orbit’s diameter of 0.66m. The sub-meter storage orbit allows us to reconstruct decayed positron momentum event-by-event, and to obtain vector of the muon spin precession. This is crucial to distinguish the muon g-2 component parallel to the magnetic field, and the EDM component perpendicular to the magnetic field, and allow us to measure these two physical quantities at a time, but independently with a same experimental setup.
In this presentation, we will introduce outline of newly developed three-dimensional spiral beam injection method to realize a new experiment at J-PARC. Two major R&D items are introduced: (1) X-Y coupling to store the beam in the axially symmetrical solenoid magnetic field (dedicated beam phase space control applying strong coupling between in the solenoidal-axial direction and the radial direction), (2) a vertical kicker device to control the beam motion from the injection trajectory to the store trajectory. We will also introduce results of demonstration experiment to judge feasibility of this new injection scheme. We successfully inject the electron beam with 0.24m diameter and store by use of a vertical kicker device, which is the same concept as original experiment. At the same time, however, several issues which should be considered towards the actual production are found and we will discuss them, too.

Speaker: Hiromi Iinuma

iinuma_spin2023_v0.pptx

202 Optimisation of Spin Coherence Time for Electric Dipole Moment measurements in a storage ring.

Electric dipole moments are very sensitive probes of physics beyond the Standard Model. The JEDI collaboration is dedicated to the search for the electric dipole moment (EDM) of charged particles making use of polarized beams in a storage ring. In order to reach the highest possible sensitivity, a fundamental parameter to be optimized is the Spin Coherence Time (SCT), i.e., the time interval within which the particles of the stored beam maintain a net polarization greater than 1/e. To identify the working conditions that maximize SCT, accurate spin-dynamics simulations have been performed using BMAD. In this study, lattices of a "prototype" storage ring, which uses combined electric and magnetic fields for bending, and a "hybrid" storage ring using only electric bending fields with magnets for focusing, are investigated. This talk presents a model of spin behaviour in frozen-spin lattices that has been verified in both situations, as well as a technique to optimize the second-order beam optics for maximum SCT at any given working point.

Speaker: Rahul Shankar (University of Ferrara and INFN)

203 Application of Spin Canceling Cell Design to Several Lattices

We have previously developed a design approach to minimize the intrinsic spin resonance for lattice. This approach involves ensuring the cancelation of spin kicks due to quadrupoles between spin precessing dipole magnets. We apply this approach to the AGS-Booster, future FCC-hh and FCC-ee Booster rings.

Speaker: Vahid Ranjbar (BNL)

SpinCellTalkSpin2023.pptx

204 Predominantlty Electric Storage Ring "E&m" for Nuclear Spin Physics

The sparsity of spin dependence data in nuclear collision physics is due to the experimental inconvenience of center of mass (CM) particle kinetic energies (KEs) required to be in the range from 100 KeV to 1 MeV in order to be comparable with Coulomb potential energy barrier heights. Small compared to all nucleon rest masses, the lab frame and the CM frame then coincide.

Particles in the 100's of KeV energy range are easily produced in vacuum, but their ranges are negligibly small in matter, and too low in energy for study in any magnetic storage ring.

To study spin dependence in nuclear scattering, one must cause the scattering to occur in what is at least a weakly relativistic moving frame of reference.

This is possible, using a predominantly electric storage ring E&m-SR with weak magnetic bending superimposed. The presence of magnetic bending makes it possible for two beams of different velocity (owing to their different particle type) to circulate in the same direction, at the same time, in the same storage ring.

The presence of ``rear-end'' collisions between two particles co-moving with substantial, but slightly different velocity in the laboratory, allows their CM KEs to be in the several 100 KeV range, yet all incident and scattered particles have convenient laboratory KEs, two orders of magnitude higher, in the tens of MeV range.

This permits incident beams to be established in pure spin states and the polarization of scattered particles measured with high analyzing power and high efficiency.

With careful tuning of E and B, certain baryon bunch pairs of different particle type, such as d and h (helion) or p and d, to have appropriately different charge, mass, and velocity such that their rigidities are identical; both beams can then co-circulate indefinitely, with different velocities.

By design, all nuclear collisions will then take place in a coordinate frame moving at convenient semi-relativistic speed in the laboratory, with CM KEs comparable with Coulomb barrier heights.

One proposed configuration has d and h beams circulating concurrently in the same storage ring,with parameters arranged such that, in the (maximally exothermic, 18.3 MeV per transmutation event) process d+h -> p+alpha, rear-end collisions always occur at an intersection point (IP) which detects the events.

Speaker: Richard Talman (Cornell University)

PredomElecSRforNuclPhys-SPIN2023-paper.pdf

PredomElecSRforNuclPhys-SPIN2023-slides.pdf

SPIN2023-RTalman-paper.pdf

SPIN2023-RTalman-paper.pdf

Future Facilities and Experiments: Future IV

Convener: Patrizia ROSSI (JEFFERSON LAB)

205 The role of vector mesons in the interpretation of single-spin asymmetries and opportunities with future studies

Vector meson (VM) production in polarized quark fragmentations has been recently studied in the context of the string+${}^3P_0$ model of hadronization. The spin effects for the production of VMs depend on the coupling of the mesons to the quarks in the fragmentation chain, which is parametrized in terms of two free parameters. One of the parameters governs the fraction of longitudinally polarized VMs produced in the fragmentation process, while the other governs the oblique polarization of VMs and is a source of Collins effect. Focusing on Collins transverse spin asymmetries in SIDIS, and using the Monte Carlo implementation of the string+${}^3P_0$ model in the Pythia event generator, we show that the contribution of VM production and decay to the measured asymmetries is large and is relevant for the interpretation of the available asymmetry data. Predictions for the Collins TSA for inclusive production of $\rho$ and K* mesons in SIDIS, a poorly measured observable but relevant for a deeper insight on the spin-dependence of the fragmentation process, at future facilities such as JLAB22 are also discussed.

Speaker: Albi Kerbizi (INFN Trieste)

SPIN2023_Kerbizi_VM.pdf

206 Status and Prospects of the Electron-Ion Collider project in China

The proposed STCF is a symmetric electron-positron beam collider designed to provide e+e− interactions at a centerof-mass energy from 2.0 to 7.0 GeV. The peaking luminosity is expected to be 0.5×10^35 cm−2s−1. STCF is expected to deliver more than 1 ab−1 of integrated luminosity per year. The huge samples could be used to make precision measurements of the properties of XYZ particles; search for new sources of CP violation in the strange-hyperon and tau−lepton sectors; make precise independent mea-surements of the Cabibbo angle (theta)c) to test the unitarity of the CKM matrix; search for anomalous decays with sensitivities extending down to the level of SM-model expectations and so on. In this talk, the physics interests will be introduced as well as the the recent progress on the project R&D.

207 New Experimental Spin-Physics Opportunities for Meson Beams

During the past several decades a large quantity of high-quality mesonic photo- and electro-production data have been measured at electromagnetic facilities worldwide. By contrast, meson-beam data for these same final states are mostly outdated, largely of poorer quality, or even non-existent, especially those involving spin asymmetries and polarizations. Thus existing meson beam results provide inadequate input to interpret, analyze, and exploit the potential of the new electromagnetic data. To achieve full benefit of these high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledge in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, new, state-of-the-art meson-beam facilities are needed. This presentation summarizes unresolved issues in hadron physics and outlines the opportunities and advances that are possible with such facilities.

Speaker: Bill Briscoe (GWU)

SPIN2023-Presentation-WJB-IS.pdf

Polarized Ion and Lepton Sources and Targets: Sources and Targets VI

Convener: Matt Poelker (JLab)

208 A polarized ^3He target for the GEn-II experiment in Hall A at Jefferson Lab

Nucleon elastic form factors encode crucial information about its charge and magnetization distributions. For many decades, nucleon form factors were studied by using unpolarized electron-nucleon cross section measurements. The advent of electron beams with higher luminosities and beam polarization coupled with large acceptance detectors, polarized targets and recoil polarimeters enabled a wealth of information on nucleon form factors over a broad range of momentum transfer (Q^2). While plenty of information is available on the proton, no data above Q^2 = 3.5 GeV^2 is available on the neutron electric form factor. Pushing the data to a higher Q^2 allows constraining spin flip GPDs and serves as a bench mark for various theoretical models. Using quasi-elastic scattering of a polarized electron beam on a polarized ^3He target, one can extract the GEn term which is proportional to the measured asymmetry from opposite electron beam helicity.

The GEn-II experiment at Jefferson lab utilizes a polarized He3 target for a high Q^2 measurement of the neutron electric form factor. The target consists of a pumping chamber (where polarization of He3 takes place), a target chamber (where e- beam interacts with the target material) and transfer tubes (which facilitate a convective flow of the polarized material). ^3He gas at ~8 atm pressure is filled into the glass cells along with Rb-K alkali mixture and narrow band diode lasers are used for polarizing the He3 using a SEOP (Spin Exchange Optical Pumping) technique. The target system used in the experiment includes multiple Helmholtz coils to create a holding field that determines the direction of polarization for the ^3He nuclei. Two polarimetry techniques are used to determine the absolute (EPR) and relative (EPR) polarization during production running. The GEn-II experiment finished taking data at three out of four kinematic settings and is scheduled for completion in the Fall of this year. A general description of the target and an overall performance will be discussed in this talk.

Speaker: Arun Tadepalli (Jefferson Lab)

GEn_target_SPIN23.pptx

209 The Polarized 7LiD Program at Jefferson Lab for Polarized Fusion Experiments at DIII-D Tokamak

Polarized fuels in a tokamak fusion reactor can increase the cross section by 50%, and the power gain of an ITER-scale fusion reactor by 75%. The question is: can polarized materials survive inside a hot fusion plasma for times long enough to reap these expected gains? An in−situ polarization survivability test in a tokamak plasma is planned to address this. In a recent proposal (see William Heidbrink's plenary talk), we plan to prepare polarized $^7$LiD pellets and $^3$He capsules for injection into a hot plasma in the DIII-D tokamak, using the D + $^3$He $\rightarrow$ α + p reaction as a test bed. The $^7$LiD pellets need to be precisely engineered with fusion specifications, irradiated with electron beams at ~185K to induce paramagnetic centers, and stored at 77K. A dilution refrigerator-based DNP polarizer suitable to the planned fusion experiment will be designed and built at Jefferson Lab. This device will load the pre-irradiated $^7$LiD pellets, at ~2mm in size, into a polarization chamber, polarize them with microwaves at ~7 Tesla and ~100 mK, and measure polarization of individual pellets before dispensing into a tokamak gas gun pellet injector. Details will be discussed.

Speaker: Xiangdong Wei

The Fusion Program at JLab-SPIN2023-v4.pptx

210 The COMPASS polarized deuteron target results in 2022

The COMPASS experiment at CERN used a transversely solid polarized deuteron target with a muon beam to measure the TMD PDFs in SIDIS in 2022.

The target system consists of a 50 mK dilution refrigerator, a 2.5 T solenoid magnet, and three sets of 70 GHz microwave systems. Solid $^6$LiD beads of the target material were contained in 3-target-cell of 30-60-30 cm long with 3 cm in diameter. The target material was produced for the first phase of COMPASS which started data taking in 2002. The longitudinal polarization of the target is obtained by the DNP method with gunn diode oscillators which are newly installed. We collected data from June to November 2022.

The polarization was determined with 10 NMR coils on the cells.
The polarization was calibrated with the thermal NMR signal at three different temperatures (1.0, 1.2 and 1.5 K).
The analysis of the thermal equilibrium NMR signal is essential to determine the polarization during DNP.

We will present the results of the analysis of the thermal deuteron NMR signals, the relaxation times during the data taking as well as performance of the new microwave synthesizers.

Speaker: Gerhard Reicherz (Ruhr-University Bochum)

COMPASS-LiD-Target-Reicherz.pdf

Spin physics in Nuclear Reactions and Nuclei: Nuclear IV

Convener: Ian Cloet (Argonne National Laboratory)

211 Non-nucleonic degrees of freedom and the spin structure of the deuteron

We demonstrate that paradigm shift from considering the deuteron as a system of a bound proton and neutron to considering it as a pseudovector composite system from which one observes emerging proton and neutron results in the possibility of probing a new “incomplete” P-statelike structure on the light front (LF). This occurs at large internal momenta, which can be probed in a high energy transfer electro-disintegration of the deuteron. Investigating the deuteron on the light front, where the vacuum fluctuations are suppressed, we found that this new structure can exist only if the deuteron contains non-nucleonic components in its ground state. We investigate the implication of this new state on polarization properties of the deuteron and demonstrate that it will result in in a strong enhancement of the tensor polarization strength of the deuteron beyond the S- and D- state predictions at large internal momenta.

Speaker: Misak Sargsian (Florida International University)

MisakSargsianSpin23.pptx

212 Quasi-Elastic Tensor Asymmetry Azz

Tensor polarization enhances sensitivity to short-range, high-momentum QCD effects, which provide important insight to the deuteron wavefunction. Knowing the properties of the deuteron’s nucleon-nucleon potential is essential for understanding short-range correlations as they are largely dependent on the tensor force that is described by the nucleon-nucleon potential. In the quasielastic region, the tensor asymmetry Azz provides a unique tool to experimentally constrain the ratio of the S- and D-state wavefunctions at large momentum. Azz was recently revisited using modern relativistic virtual nucleon and light-cone methods, which predict differences up to a factor of two in Azz that can be distinguished experimentally. Additionally, the calculations were done using multiple wavefunctions that diverge at large x, making Azz an ideal observable for providing new constraints. The upcoming Jefferson Lab experiment E12-15-005 to measure Azz will be discussed.

Speaker: Prof. Elena Long (University of New Hampshire)

ELong-SPIN_2023.pptx

213 Testing SRC Universality with Meson Photoproduction

Nuclear Short Range Correlations (SRCs) are pairs of nucleons which exist at short relative distance and high relative momentum within the nucleus. These SRC pairs have significant impacts on nuclear structure and have been extensively studied using hard quasi-elastic electron-scattering data. Interpretations of these hard scattering data rely heavily on our understanding of reaction mechanisms at play in electron-scattering measurements, as well as assumptions of of factorization between the reaction and the nuclear ground-state. In fall of 2021, our collaboration took data in Hall D of Jefferson Lab, using a real photon beam incident on nuclear targets to independently measure the properties of nuclear SRCs. Here we present the measurement of SRC breakup events in this data using quasi-elastic ρ- meson photoproduction from correlated neutrons in deuterium, helium, and carbon nuclei, along with comparisons to the GCF predictions. We use the ab-initio calculations to show consistency between the electron- and photo-scattering measurements; in this, we provide evidence for the universality of SRC properties across reactions, showing that several different hard reactions proceeding on correlated nucleons may be consistently explained using a single model.

Speaker: Jackson Pybus (MIT)

SRC Universality.pdf

12:40 PM Lunch Break

3:00 PM Excursion

6:30 PM Conference Dinner

Thursday, September 28

Plenary: TMD I

Convener: Andrea Signori (University of Turin and INFN)

214 Three-dimensional nucleon structure

I will discuss the three-dimensional (3D) nucleon structure encoded in the Transverse Momentum Dependent distributions, providing an overview of the current knowledge. Using several examples, I will demonstrate the significance of the 3D structure and its relation to other topics in hadronic physics.

Speaker: Alexei Prokudin (JLab)

Prokudin_SPIN23.pdf

215 Updates on phenomenology

A new era for the exploration of hadron structure has begun with the Jefferson Lab 12 GeV program and the planned Electron Ion Collider. The new generation of experiments will allow us to probe the quantum correlation function (QCFs) of quarks and gluons that emerges from the theory of strong interactions. Since QCFs are not direct physical observables, they need to be reconstructed from experimental data using the framework of QCD factorization that stress test in a self consistent manner the predictive power of QCD and the universality of QCFs. In this talk we will discuss recent progress on phenomenology in the exploration of nucleon’s spin structures.

Speaker: Nobuo Sato (Jefferson Lab)

SPIN.pdf

216 TMD program at JLab

We present ongoing studies and some future
measurements with hadrons in electroproduction at Jefferson Lab

Speaker: Harut Avagyan (Jefferson Lab)

avakian-spin2023.pdf

avakian-spin2023.ppt

10:30 AM Coffee Break

Plenary: TMD II

Convener: Oleg Eyser (BNL)

217 The COMPASS Spin Program

COMPASS is a fixed target high energy physics experiment located at the M2 beamline (SPS, North Area) at CERN. It is the longest-running CERN experiment (2002-2022), with a unique and diverse physics programme focused on nucleon structure and spectroscopy measurements.
Experimental results obtained by COMPASS during phase-I (2002-2011) and phase-II (2012-2022) for a broad spectrum of nucleon spin structure-related DIS and Drell-Yan measurements play an essential role in the general understanding of the three-dimensional nature of the nucleon. In 2022, the experiment performed its last highly successful data-taking dedicated to the study of the d-quark transversity PDF and other transverse spin phenomena in semi-inclusive DIS measurements with a 160 GeV/c muon beam and a transversely polarized deuteron target.
This talk will review selected highlights from the COMPASS legacy on nucleon spin structure studies and address recent results and prospects

Speaker: Dr Parsamyan Bakur (AANL, CERN and INFN Turin section)

Parsamyan_SPIN2023.pdf

218 The STAR Forward Program

Speaker: Prof. Carl Gagliardi (Texas A&M)

STAR_Forward_Upgrade_SPIN-2023.pdf

219 The ePIC Detector and Physics

Speaker: Barak Schmookler (UC Riverside)

epic_spin2023.pdf

12:30 PM Lunch Break

Plenary: TMD III

Convener: Alexei Prokudin (JLab)

220 Lattice calculation of TMD physics

Recently years have seen significant progress in the first-principles calculation of TMD physics from lattice QCD. In this talk, I will describe the theoretical method for calculating both quark and gluon TMDs, which has been developed under the framework of large-momentum effective theory. I will then review its most recent applications to the non-perturbative quark TMDs and their rapidity evolution anomalous dimension, i.e., the Collins-Soper kernel, and discuss the control and improvement of systematic uncertainties in such calculations.

Speaker: Yong Zhao (Argonne National Laboratory)

Spin2023_yongzhao_2.pdf

Spin2023_yongzhao.pdf

Spin2023_yongzhao.pdf

221 Theoretical Advances in Jet Substructure

Jets of hadrons produced at high-energy colliders provide experimental access to the dynamics of asymptotically free quarks and gluons and their confinement into hadrons. We highlight recent developments in the theoretical understanding of jet substructure, focusing in particular on the "energy correlator" observables, and their application to the spin physics program.

Speaker: Ian Moult (Yale)

IanMoult_spin_2023.pdf

iXVVIdna.png

222 Jets for Spin Physics - An Experimental Perspective

Since key theoretical developments 15 years ago that allowed more rigorous comparison of jets between experiment and theory, jets have become a powerful multipurpose tool in high-energy nuclear and particle physics. Linking partonic and hadronic degrees of freedom, they can provide access to spin-spin and spin-momentum correlations both in the nucleon and in the process of hadronization. Exploring novel ideas using jets to probe spin-dependent phenomena with data from existing facilities will better position us to fully exploit the potential of jet measurements at the Electron-Ion Collider in the 2030s.

Speaker: Prof. Christine Aidala (University of Michigan)

AidalaSpin2023updated.pdf

3:30 PM Coffee Break

Plenary: Low Energy

223 The Proton Radius Puzzle: Are We Still Puzzled?

The proton radius puzzle began in 2010 when the CREMA Collaboration released their measurement of the proton radius (Pohl et. al (2010)) from muonic hydrogen spectroscopy: rp=0.84184(67) fm, This was five standard deviations smaller that the accepted CODATA value at that time (0.8768(69) fm), and sparked an enduring and intriguing puzzle. This puzzle has been addressed in repeated electron scattering measurements seeking to go lower in Q2, such as PRad at Jefferson Lab, and the Mainz Initial State Radiation experiment. There has also been a plethora of new atomic hydrogen spectroscopy experiments, and some more muonic atom spectroscopy. The results of these measurements have served to further add to the puzzle, with even CODATA saying that more and different measurements are needed. New experiments are planned and underway which seek to address this challenge in new ways. We will summarize the current status and future outlook of proton radius investigations.

Speaker: Prof. Evangeline J. Downie (George Washington University)

EJDownie_Radius_Final.pdf

224 Current Status of g-2

Speaker: Prof. Aida El-Khadra (University of Illinois)

El-Khadra_Spin2023.pdf

225 Spin physics at MAMI/MESA

The 1.6 GeV electron accelerator is operated by the institute for nuclear physics on the campus of the Mainz University. It will be complemented by a high intensity low energy accelerator MESA which can be operated in energy recovery mode. The spin physics program at MAMI and MESA will be summarized.

Speaker: Prof. Frank Maas

Maas_SPIN2023_Durham_MAMI_MESA.pdf

226 Search for Electric Dipole Moments and Axions/ALPs of charged particles using storage rings

The study of permanent and oscillating Electric Dipole Moments (EDMs) of
fundamental particles for charged hadronic systems such as proton and deuteron (possibly also 3 He) can help to find answers to two of the most important current scientific questions in particle physics and cosmology: (i) What happened to antimatter after the Big Bang? and (ii) What is dark matter?
The current Standard Model of Cosmology (SMC) is not able to explain the
observed asymmetry between matter and antimatter in our universe. Obviously, physics beyond the SMC is needed, which can be explored either by using highest energies (e.g., at LHC) or by striving for highest precision and sensitivity (e.g., in the search for electric dipole moments). Permanent electric dipole moments (EDMs) and oscillating EDMs (oEDMs) caused by axions or axion-like particles (ALPs) violate both time reversal ($T$) and parity invariance ($P$) and are also $CP$-violating via the $CPT$ theorem. The discovery of EDMs or ALPs far above the immeasurably small SMC background would thus be strong evidence for physics beyond the SMC.
While many EDM searches focus on neutral systems (neutrons, atoms, and
molecules), storage rings offer the possibility to measure EDMs/ALPs of charged particles by observing their influence on the spin motion in the ring [1]. Direct searches for proton and deuteron EDMs hold the potential to achieve sensitivities of the order of $10^{-29}$ e cm. In this talk, the JEDI experiments for the first direct measurement of deuteron EDMs and the first search for axion-like particles in a storage ring will be presented and recent results will be discussed.
The next inevitable step on the way to a precision EDM facility is the construction of a prototype storage ring (PSR), comprising both an all-electric version and a hybrid ring in which the electric fields are supplemented by magnetic fields. The technical design of the PSR is the main goal (beam energy of about 30 − 40 MeV, circumference of about 100 m), and once available, it should demonstrate all remaining ambiguities and technologies and enable the first direct proton EDM measurement with sensitivity comparable to that of the neutron. Upon successful completion, the subsequent precision EDM facility (energy 230 MeV, circumference about 500 m) may eventually be able to improve the current static EDM limit of the neutron by up to three orders of magnitude and open the possibility for a unique discovery.

[1] F. Abusaif et al. Storage ring to search for electric dipole moments of charged particles: Feasibility study. CERN Yellow Reports: Monographs, 2021-003. CERN, Geneva, Jan 2021. URL https://cds.cern.ch/record/2654645.

Speaker: Frank Rathmann (IKP, Forschungszentrum Jülich)

JEDI-Spin2023_Rathmann_02.10.2023.pdf

Poster Session: Poster Session and Reception

227 Relativistic hydrodynamics with spin in EM fields

We extend the classical phase-space distribution function to include the spin and electromagnetic fields coupling and derive the modified constitutive relations for charge current, energy-momentum tensor, and spin tensor. Because of the coupling, the new tensors receive corrections to their perfect fluid counterparts and make the background and spin fluid equations of motion communicate with each other. We investigate special cases which are relevant in high-energy heavy-ion collisions, including baryon-free matter and large mass limits. Using Bjorken symmetries, we find that spin polarization increases with increasing magnetic field for an initially positive baryon chemical potential. The corrections derived in this framework may help to explain the splitting observed in Lambda hyperons spin polarization measurements.

Speaker: Rajeev Singh (Center for Nuclear Theory, Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA)

228 Impact of Imperfection Spin Resonance Strength on Depolarization in RHIC

Using a simple smooth step like function of emittance developed from direct spin-orbit tracking simulations, we characterize the polarization performance from previous RHIC runs.

Speaker: Katherine Ranjbar (Port Jefferson High School)

229 Thermal shear and $\Lambda$ polarization in heavy-ion collisions

The polarization of the $\Lambda$ hyperon is a key observable in the study of the Quark-Gluon Plasma produced in heavy ion collisions. Recent studies have highlighted the importance of considering the thermal shear tensor, the symmetric derivative of the four-temperature vector, in the calculations of polarization as it can accommodate the discrepancy between theoretical predictions and experimental data. We review the derivation of the thermal shear tensor contribution to the $\Lambda$ polarization and perform numerical simulations of heavy-ion collisions at RHIC and LHC energies using the hybrid SMASH+vHLLE. Polarization is calculated in different freeze-out scenarios including the feed-down corrections. We discuss the dependence of the results on the initial conditions and collision energy and compare them with the available experimental data.

Speaker: Andrea Palermo (Frankfurt UNiversity)

230 Laser-Induced Polarization for the Electron-Ion Collider

The use of an intense ultrashort laser pulse to induce electron polarization has been proposed in existing literature[1]. Utilizing the Python programming language, a code has been developed to recreate the local constant crossed-field approximation (LCFA) with the aim of determining values for transverse polarization given a nonzero initial polarization. It has been shown that over multiple laser shots, lower values of the quantum efficiency parameter are associated with higher transverse polarization output, yet require a greater number of shots to attain maximal polarization. Moreover, the quantum efficiency parameter has been redefined as a function of intensity for Ti:sapphire laser necessary to induce polarization in the Electron-Ion Collider.

[1] D.~Seipt,``Volkov States and Non-linear Compton Scattering in Short and Intense Laser Pulses,'' doi:10.3204/DESY-PROC-2016-04/Seipt

Speaker: Katherine Ranjbar (Port Jefferson High School)

231 A new distributed Bragg reflector for MOCVD-grown spin polarized electron sources

Photocathodes fabricated with a distributed Bragg reflector have been known to provide higher quantum efficiency, because the light entering the photocathode can reflect many times between the DBR and the front surface of the photocathode, providing more absorption of the incident laser light. Our team previously demonstrated enhanced quantum efficiency from a DBR photocathode using the process of molecular beam epitaxy (MBE), with the DBR composed of multiple layer pairs of AlAs0.61P0.39/ GaAs0.65P0.35. In this work, we report excellent results from a photocathode fabricated via metal organic chemical vapor deposition (MOCVD), and with the DBR composed of In0.30 Al0.70/ GaAs0.65P0.35. Overall, our devices achieved up to 82% polarization and 2.9% quantum efficiency. This presentation describes fabrication issues related to MOCVD, the benefits of this new DBR structure and prospects for higher quantum efficiency.

Speaker: Dr Sylvain Marsillac (Old Dominion University)

232 Background-free detection of polarization transfer from hyperpolarized 129Xe to thermally polarized 19F at ultra-low magnetic field

Introduction

Nuclear spin hyperpolarization (HP) enhances the NMR signal by several orders of magnitude by bringing the spins out of thermal equilibrium, populating one of the spin states in favor of the other. Enhanced spin polarization is especially advantageous at ultra-low magnetic field strengths, where thermal polarization may often result in NMR signal intensities that are indistinguishable from noise.

Among all nuclei, xenon-129 is a remarkable NMR probe as it is inert, soluble in biological tissues, and its hyperpolarization lifetime can last up to a few hours. Xenon-129 hyperpolarization is accomplished via spin-exchange optical pumping (SEOP), whereby spin order of a high-power laser is indirectly transferred to the $^{129}$Xe nucleus. The long-lasting $^{129}$Xe spin order may then be transferred to other fast-relaxing nuclei via the spin polarization-induced nuclear Overhauser effect (SPINOE) [1].

Previous works investigated the transfer of spin order from hyperpolarized $^{129}$Xe to thermally polarized $^{1}$H [2, 3]. Our investigation examines the continuous transfer of spin order from HP $^{129}$Xe to thermally polarized $^{19}$F via SPINOE in the ultra-low field regime. Unlike previous high field investigations, SPINOE enhancements at low field are directly detectable without the need to destroy background thermal polarization. Simultaneous detection of both nuclei enables the determination of cross-relaxation rates and the molecular dynamics of the SPINOE phenomenon.

Methods

All measurements were performed on a lab-built NMR spectrometer operating in the 2 mT regime using a dual-resonance volume coil capable of simultaneously exciting and detecting $^{129}$Xe and $^{19}$F. HP $^{129}$Xe was bubbled into 2 mL hexafluorobenzene (C$_{6}$F$_{6}$) in a 5 mm NMR tube for 6 seconds, prior to acquiring after a delay to allow for spin exchange. The low thermal spin polarization, which at ultra-low field is on the order of 10$^{-9}$, obviates the need for pre-saturation pulses to destroy thermal $^{19}$F signal. An RF train destroyed any remaining $^{129}$Xe and $^{19}$F hyperpolarization prior to subsequent acquisitions.

Results and Discussion

The SPINOE-enhanced $^{19}$F signal was found to persist for over 200 s, in stark contrast to its short T$_{1}$ of 1.1 s at 2 mT. This long-lasting signal enhancement was due to the continuous transfer of polarization from the slowly relaxing $^{129}$Xe spins, the T$_{1}$ of which in hexafluorobenzene is 144 s. The SPINOE-induced NMR signal enhancement was measured to be ε = 178, while the integrated enhancement, achieved across 64 averages, was measured to be ε = 8459. Finally, fitting of the $^{129}$Xe and $^{19}$F signal vs. time curves yielded a σ = $3.40 *10^{-5}$ s$^{-1}$M$^{-1}$ cross-relaxation rate, higher than that previously reported for $^{129}$Xe$-$$^{1}$H spin exchange.

Conclusion

The NMR signal of thermally polarized nuclei is largely undetectable at ultra-low field strengths by standard induction techniques typically used at high field. Here we demonstrate a versatile method to continuously transfer the polarization of $^{129}$Xe, efficiently polarized by SEOP, to other nuclei. This transfer of polarization results in a significantly enhanced NMR signal of the target nucleus and an apparent polarization that lasts beyond the intrinsic T$_{1}$ of the targeted spins.

References

[1] Song, Y.Q. (1999). Spin polarization-induced nuclear Overhauser effect: An application of spin-polarized xenon and helium. Concepts in Magnetic Resonance, 12(1), 6-20.
[2] Appelt, S., Häsing, F. W., Baer-Lang, S., Shah, N. J., & Blümich, B. (n.d.). Proton magnetization enhancement of solvents with hyperpolarized xenon in very low-magnetic fields. Chemical Physics Letters, 348, 263-269.
[3] Song, Y.Q., Goodson, B. M., Taylor, R. E., Laws, D. D., Navon, G., & Pines, A. (1997). Selective Enhancement of NMR Signals for α-Cyclodextrin with Laser-Polarized Xenon. Angewandte Chemie, 36(21), 2368-2370.

Speaker: Sebastian Atalla (UNC Chapel Hill)

233 Improving Λ Signal Extraction with Domain Adaptation via Normalizing Flows

Normalizing Flows have been implemented across several fields, notably in image generation and recently high energy and nuclear physics. The present study investigates the ability of flow based neural networks to improve signal extraction of Λ Hyperons at CLAS12. Normalizing Flows enable density estimation by learning how to transform a simple distribution with a known PDF to a complex distribution whose PDF is unknown. These neural networks can help model complex PDFs that describe physics processes, enabling uses such as event generation. Λ signal extraction has been improved through the use of classifier networks, but differences in simulation and data domains limit classifier performance; this study utilizes the flows for domain adaptation between Monte Carlo simulation and data. We were successful in training a flow network to transform between the latent physics space and a normal distribution. We also found that applying the flows lessened the dependence of the figure of merit on the cut on the classifier output, meaning that there was a broader range where the cut results in a similar figure of merit. In future studies, when the figure of merit is unattainable, the cut on the classifier output can be made without exact precision while maintaining an optimal signal extraction; without using flows the cut must be made more precisely.

Speaker: Matthew McEneaney (Duke University)

Normalizing_Flows_Poster_mk3-4 (1).pdf

234 Interpolating the ‘t Hooft model between Instant and Light-Front dynamics in the Coulomb Gauge

The 1+1D model of quantum chromodynamics (QCD) in the infinite number of colors, or ‘t Hooft model, is interpolated between the instant form dynamics (IFD) and the light-front dynamics (LFD) using an interpolation parameter δ in the interpolating Coulomb gauge which links the Coulomb gauge (A⁰ = 0) in IFD and the light-front gauge (A+ = 0). While calculations such as these were performed [1] in the interpolating axial gauge which links the the spatial or axial gauge (A1 = 0) in IFD and the light-front gauge (A+ = 0), there are a number of benefits to the Coulomb gauge that cannot be ignored. All degrees of freedom are physical, making this an ideal choice for finding the bound-state equations and for renormalizability. Using this parameter δ, we find the mass gap equation using both hamiltonian formalism and feynman diagram analysis, noting that it reproduces both the results for IFD and LFD in the Coulomb gauge and the light-front gauge, respectively. We then derive the quark-antiquark bound-state equation in the interpolating dynamics using the dressed fermion propagator and compare with results obtained in the interpolating axial gauge [1]. The meson mass spectra of such mesons that follow Regge trajectories are independent of δ, which are observed in both IFD and LFD calculations using the interpolating axial gauge condition. We also obtain the bound-state wave functions and compare the results between the interpolating coulomb gauge and the interpolating axial gauge. Since QCD respects the gauge symmetry, these results should all be independent of the gauge choice. These wavefunctions are particularly useful in the calculation of quasi-parton distribution functions (quasi-PDFs), in which we can produce an alternative approach to the quasi-PDFs not only with the frame dependence but also with the δ dependence. The Coulomb gauge in IFD is particularly interesting in this way, because the A0 component is renormalization group invariant [2]. Thus, the interpolation may lead to an alternative quasi-PDF that can be implemented in the lattice QCD without suffering from the large momentum boost.

1. Ma, Bailing, and Chueng-Ryong Ji. “Interpolating ’t Hooft Model between Instant and Front Forms.” Physical Review D, vol. 104, no. 3, 2021, https://doi.org/10.1103/physrevd.104.036004.

2. Zwanziger, D. (1998). Coulomb-Gauge in QCD: Renormalization and confinement. Progress of Theoretical Physics Supplement, 131, 233-242. https://doi.org/10.1143/ptps.131.233

Speaker: Hunter Duggin (North Carolina State University)

235 Measuring Transversity in Di-Hadron Correlations with the ePIC Detector

This contribution will show projections of transverse single spin asymmetries sensitive to transversity that can be measured with the ePIC detector at the future EIC

Speaker: Seth Reiman

236 Mechanisms of polarized $J/\psi$ production in NRQCD

We compare the relative contributions of light quark fragmentation and photon-gluon fusion to the production of polarized $J/\psi$ via semi-inclusive DIS. We use a TMD framework for fragmentation, and match the production cross sections onto NRQCD. Both color singlet and color octet mechanisms contribute. We plot the cross sections differential in $P_\perp$, for both unpolarized and longitudinally polarized $J/\psi$, in various kinematic regimes to find where each mechanism is dominant. This can help determine where the gluon TMD PDFs can be accessed, which will be relevant in the era of the upcoming EIC.

Speaker: Reed Hodges

237 Modeling the CEBAF Injector at 200 kV: Investigating K-Long Beam Conditions with and without Wien Filter

The upcoming K-Long experiment [1] ain Hall D at Jefferson Lab presents unique beam requirements, featuring a significantly low bunch repetition rate and an unusually high bunch charge. This experiment, which utilizes the CEBAF accelerator in conjunction with the GlueX experimental setup, aims to study strange hadron spectroscopy by measuring the differential cross section and polarizations of produced hyperons such as Λ, Σ, Ξ, and Ω. By directing an intense K-Long beam towards the LD2/LH2 target, new and valuable data can be obtained. To optimize the CEBAF injector specifically for this experiment, we employed Multi-Objective Genetic Optimization (MGO) using General Particle Tracer (GPT) simulations. Through this approach, we determined the optimal magnetic elements and radiofrequency (RF) settings required to achieve a K-Long bunch charge of 0.64 pC at an energy of 200 kV. We conducted simulations with both the Wien Filter turned on and off to examine its impact on the beam. Furthermore, we investigated the transmission efficiency and beam characteristics of electron beams with varying charge per bunch through the injector, considering the simultaneous operation of all four CEBAF Halls. The results of our study offer valuable insights and guidance for optimizing the CEBAF injector not only for the Jefferson Lab K-Long experiment but also for other experiments that entail similar beam conditions.

Speaker: Sunil Pokharel (Old Dominion University)

238 Preparations for spin physics at sPHENIX

The sPHENIX experiment, currently in commissioning at the Relativistic Heavy Ion Collider at BNL, is a new detector built for jet, direct photon, and hadron measurements. Next year, sPHENIX will take data from transversely polarized p+p and p+Au collisions. Transverse single spin asymmetry (TSSA) measurements at sPHENIX from the 2024 run will explore the parton dynamics within transversely polarized protons described in the collinear higher-twist and transverse-momentum dependent (TMD) frameworks. Direct photon, heavy flavor, and inclusive jet TSSA’s will probe the initial-state multi parton correlations that are related to moments of the Sivers TMD parton distribution function (PDF), which describes the correlation between parton transverse momentum and nucleon transverse spin. Measurements of hadron-in-jet and di-hadron asymmetries will explore the transversity PDF, which describes the distribution of transversely polarized quarks in a transversely polarized nucleon. Additionally, single spin asymmetries of hadrons in both p+p and p+Au can further clarify the presence of nuclear modification effects hinted at in previous measurements from earlier experiments. In preparation for spin physics at sPHENIX, dedicated hardware must be installed and online monitoring must be developed to ensure quality spin data. This poster will give an overview of spin physics at sPHENIX and discuss the preparations of the hardware and software necessary for polarized data taking.

Speaker: Devon Loomis (University of Michigan)

239 Propagation properties of spin polarization

The propagation properties of spin degrees of freedom are analyzed in the framework of relativistic hydrodynamics with spin based on the de Groot van Leeuwen–van Weert definitions of the energy-momentum and spin tensors. We derive the analytical expression for the spin wave velocity for arbitrary statistics and show that it goes to half the speed of light in the ultrarelativistic limit. We find that only the transverse degrees of freedom propagate, analogously to electromagnetic waves. Finally, we consider the effect of dissipative corrections and calculate the damping coefficients for the case of Maxwell-Jüttner statistics.

Speaker: Dr Rajeev Singh (Center for Nuclear Theory, Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA)

240 Sivers asymmetries in SIDIS and Drell Yan at COMPASS

The COMPASS experiment took data between 2000 and 2022 using the SPS muon and hadron beams in the CERN North Area and fixed unpolarized and polarized nuclear targets. It remains one of the most impactful experiments in the field due to its contributions in exploring the spin structure of the nucleon. One of the key objectives of COMPASS is to investigate transverse momentum dependent PDFs by measuring transverse single-spin asymmetries in semi-inclusive deep inelastic scattering and the Drell-Yan process. Of particular interest is the Sivers TMD PDF, which is connected to spin-orbit correlations in the proton and is expected to change sign between SIDIS and DY, a process dependence that is unusual for PDFs. This poster will present recent results of COMPASS Sivers asymmetry measurements in SIDIS and DY.

Speaker: Athira Vijayakumar (UIUC)

241 Small-x Helicity Evolution: Disambiguation of Bimodal g_1^p

Novel improvements to small-$x$ helicity evolution equations have been incorporated into a global analysis of both DIS and SIDIS cross sections. This global analysis uncovered a bimodality of solutions for the asymptotic ($x \to 0 $) sign of the $g_1$ structure function of the proton, and a novel correlation it has with the quark and gluon helicity parton distribution functions (hPDFs), $\Delta\Sigma$ and $\Delta G$. In this poster I will discuss the disambiguation of this bimodality, and some potential avenues we can take to resolve this degeneracy in the future.

Speaker: Nicholas Baldonado (New Mexico State University)

242 The sPHENIX Cold QCD Program

The sPHENIX experiment is a new detector at BNL's Relativistic Heavy Ion Collider. Designed for studies of the quark-gluon plasma produced in heavy ion collisions with high-pT jet and heavy flavor probes, sPHENIX will also enable an array of cold QCD measurements in polarized p+p and p+Au collisions. The measurements of transverse spin asymmetries in the production of photons, mesons, and jets will contribute to our understanding of transverse-momentum dependent (TMD) and related collinear higher-twist effects in the nucleon, with the possibility of also studying effects of nuclear modification. The jet physics program particularly relies on the sPHENIX calorimeter system, which consists of large-acceptance electromagnetic and hadronic sections designed for high-resolution measurements of photons, electrons, hadrons, and jets. This poster will comment on the cold QCD opportunities at sPHENIX and will present the status of commissioning the electromagnetic calorimeter, which is in full swing as of summer 2023 with the first Au+Au beams colliding in sPHENIX.

Speaker: Gregory Mattson (University of Illinois at Urbana-Champaign)

243 Transverse Single-Spin Asymmetries in Single-Inclusive Pion Production from Lepton-Nucleon Collisions with Unpolarized Next-to-Leading Order Corrections​

During collisions between leptons and transversely polarized nucleons at high energy, the left-right asymmetric formation of hadrons can be probed. These so-called transverse single-spin asymmetries AN are the subject of our work. One issue for lower-energy fixed-target experiments is the possible need for next-to-leading order (NLO) corrections. Therefore, to create plausible predictions of these asymmetries, we aim to include NLO corrections to the spin-averaged cross section that enters the denominator of AN. Comparison with data then may indicate the size of NLO corrections for the transversely polarized cross section in the numerator, which have not been fully worked out yet. We use recent phenomenological extractions of quark-gluon-quark (Sivers- and Collins-like) functions in our analysis to describe data from HERMES as well as present predictions for JLab12, COMPASS, and future Electron-Ion Collider experiments.

Speaker: Penn Smith

Friday, September 29

Plenary: GPDs

Convener: Paweł Sznajder (National Centre for Nuclear Research)

244 What are GPDs and how to access them on Lattice QCD?

Recent advancements have facilitated the approximate computation of light-cone correlation functions in lattice QCD through the evaluation of their Euclidean counterparts. In this presentation, we will provide a brief overview of these significant developments that have direct implications for Generalized Parton Distributions.

Speaker: Shohini Bhattacharya (Temple University)

Spin_2023_Final_SB.pdf

Spin_2023_Final_SB.pptx

245 Experimental aspects of GPDs

Generalized Parton Distributions (GPDs) are nowadays the object of an intense effort of research, in the perspective of understanding nucleon structure. They describe the correlations between the longitudinal momentum and the transverse spatial position of the partons inside the nucleon and they can give access to the contribution of the orbital momentum of the quarks to the nucleon spin.
Deeply Virtual Compton scattering (DVCS), the electroproduction on the nucleon, at the quark level, of a real photon, is the process more directly interpretable in terms of GPDs of the nucleon. Depending on the target nucleon (proton or neutron) and on the DVCS observable extracted (cross sections, target- or beam-spin asymmetries, …), different sensitivity to the various GPDs for each quark flavor can be exploited. GPDs can also be accessed in other reactions, such as Timelike Compton Scattering, Double DVCS, or the exclusive electroproduction of mesons.
This talk will provide an overview on recent and new, promising, GPD-related experimental results obtained at Jefferson Lab with a 12-GeV electron beam, for various target types and final states. These data open the way to a “tomographic” representation of the structure of the nucleon, allowing the extraction of transverse space densities of the quarks at fixed longitudinal momentum, as well as providing an insight on the distribution of forces inside the nucleon.
The perspectives for future JLab experiments using a polarized positrons beam will also be outlined.

Speaker: Silvia Niccolai (IJCLab Orsay)

SPIN2023_niccolai.pdf

246 Probing parton distributions in ep and ultra-peripheral collisions

Ultra-Peripheral Collisions (UPCs) at the LHC are the highest energy photon-proton and photon-nucleus collisions accessible anywhere, while the future EIC will collide electrons with protons and nuclei, allowing high-precision measurements over a wide range of Q^2. These collisions are important probes of structure functions and generalized parton distributions (GPDs), with the capability to reach small Bjorken-x values where shadowing and saturation may be important. In this talk, I will discuss how UPC and EIC measurements can be used to measure parton distributions, survey recent results, and discuss some of the theoretical and experimental challenges of these measurements.

Speaker: Spencer Klein (Lawrence Berkeley National Laboratory)

Spin2023KleinGPDs andPDsinUPCs and theEIC.pdf

247 From nucleon to nuclear generalized parton distributions

Coherent exclusive reactions with nuclei give access to nuclear generalized parton distributions (GDPs) which can be used to perform a three-dimensional tomography of bound nuclear states in quark and gluon degrees freedom. I will give an overview of existing phenomenology on nuclear GPDs, highlighting that for the lightest nuclei we have targets that have a simpler (4He, spin zero) and richer (deuteron, spin 1) GPD structure. Additionally, in incoherent exclusive reactions on nuclei, medium modifications of bound nucleon GPDs can be probed.
I will discuss upcoming measurements at existing (JLab) and future (electron-ion collider) facilities that will provide measurements for these reactions.

Speaker: Wim Cosyn (Florida International University)

Spin23_Cosyn_nuclGPD.pdf

10:30 AM Coffee Break

Plenary: Heavy Ions

Convener: Zuo-tang Liang (Shandong University)

248 Spin in heavy Ion Collisions - Theory

Huge orbital angular momenta (OAM) are produced perpendicular to the reaction plane in non-central high energy heavy-ion collisions, and part of such huge OAM are tranferred to the hot and dense matter created in collisions. Due to the shear of the longitudinal flow particles with spins can be polarized via the spin-orbit coupling in particle scatterings. Such a type of spin polarization with respect to the reaction plane is called the global polarization and is different from the particle's polarization with respect to the production plane which depends on the particle's momentum. The global spin polarization of $\Lambda$ and $\bar{\Lambda}$ has been measured by the STAR collaboration in Au+Au collisions at 7.7 − 200 GeV. The magnitude of the global spin polarization is about 2% at 7.7 GeV to about 0.3% at 200 GeV. Another important work in this field is the first measurement by STAR collaboration on nonvanishing global spin alignment of $\phi$ mesons in heavy ion collisions. The STAR data for the global spin alignment of $\phi$ mesons show a surprisingly large positive deviation from 1/3, which may indicate the effect of the local correlation or fluctuation of strong force fields. In this talk we will give an overview on experimental and theoretical developments that have been made in the study of global spin phenomena in heavy ion collisions.

Speaker: Prof. Qun Wang (University of Science and Technology of China)

wang-qun-spin-2023-1.pdf

249 Spin in Heavy Ion Collisions - Experimental Review

The study of spin dynamics in heavy ion collisions has emerged as a pivotal avenue for comprehending the intricate interactions of fundamental strong force as well as the angular momentum of subatomic particles. This talk delves into the realm of spin physics within the context of high-energy heavy ion collisions. We explore the multifaceted roles that spin plays in elucidating the properties of the quark-gluon plasma (QGP), a transient state of matter that existed microseconds after the Big Bang. This talk provides an overview of the experimental progress regarding the global spin effects in heavy ion collisions. Specifically we will discuss the global polarization of hyperons and the global spin alignment of vector mesons. We will also delve into how these phenomena arise as consequences of the complex dynamics of quarks and gluons within the fireball created in these collisions. This investigation holds the potential to provide insights to the properties of the strongly interacting QGP matter.

Speaker: Aihong Tang (Brookhaven National Laboratory)

ATang_SPIN2023.pptx

250 Global Analyses of Polarized DIS & SIDIS from Small-x Evolution

Recent developments in the theory of polarized scattering in the small-$x$ regime have led to the construction of novel evolution equations for helicity at small $x$. In recent years, these small-$x$ helicity evolution equations have been used in global analyses of inclusive DIS and now SIDIS cross sections, providing a formalism capable of predicting the unmeasured spin hiding below the lowest accessible $x$. In this talk, I will summarize the theory of spin at small $x$ and the status of its application to global analyses, with an eye toward the future electron-ion collider.

Speaker: Matthew Sievert (New Mexico State University)

Sievert_SPIN_2023.pdf

Sievert_SPIN_2023.pptx

12:30 PM Lunch Break

Plenary: Inclusive/LHC

Convener: Sebastian Kuhn (Old Dominion University)

251 Spin Structure Program at Jefferson Lab

High performance polarized beam and targets at JLab enabled an extensive program to measure nucleon spin structure functions with high precision. This talk will highlight the recent JLab spin experiments, including the measurement of the neutron spin asymmetry (A1n) in the valance quark (high-x) region and the measurement of the neutron spin moment d2 in medium-high Q2 region to study quark-gluon correlations. Recent results on spin moments at low Q2 (spin sum rules and spin polarizabilities) for both the proton and neutron will also be presented.

Speaker: Dr Jian-ping Chen (JLab)

Chen-Spin2023.pdf

252 News on the nucleon's helicity structure

We review the current status of the nucleon's helicity PDFs. We describe
recent progress on "global" analysis of the distributions, highlighting
advances on the theoretical side especially in terms of higher-order
perturbative calculations. We discuss the relevance of these advances
for the spin program at the future EIC.

Speaker: Werner Vogelsang (Univ. of Tübingen)

Spin-2023-Vogelsang.pdf

253 Fixed Target Program at the LHC

Fixed-target pp and pA collisions with a proton beam at the TeV scale provide unique laboratories for studying of the nucleon’s internal dynamics and, more in general, for investigating the complex phenomena that arise in the non-perturbative regime of QCD. Due to the significant boost of the reaction products in the laboratory frame, fixed-target collisions allow to access the poorly explored backward center-of-mass rapidity region, corresponding to the high x-Bjorken and high negative x-Feynman regimes. Thanks to its forward acceptance and outstanding performance, the LHCb detector at the LHC is perfectly suited for reconstructing particles produced in fixed-target collisions, simultaneous with the beam-beam interactions, at energies varying from √s_NN=72 GeV to √s=115 GeV. The recently installed unpolarised fixed-target system (SMOG2) paves the way to this new technology at LHC, facilitating quantitative searches also using rare probes like c- or b-quarks. In addition, SMOG2 will serve as R&D for the proposed polarised gas target project, LHCspin. This presentation provides an overview of the unpolarised results and outlines the future polarised project.

Speaker: Pasquale Di Nezza (INFN Frascati)

FT-LHC P.DiNezza - Spin 2023.pdf

3:30 PM Coffee Break

Plenary: Instrumentation/Future

Convener: Patrizia ROSSI (JEFFERSON LAB)

254 Willy Haeberli’s Early Research: Developing and Using Accelerated Spin-Polarized Beams

Willy Haeberli left us a rich 50-year nuclear polarization physics legacy. He trained generations of students, post-docs, and international collaborators in the intracacies of nuclear spin physics measurements. This talk will reflect on my time spent working in Willy’s large University of Wisconsin research group in the 1960s. His insight guided our development of polarized ion sources and experimental polarization techniques ... early seeds in his long, productive career of research accomplishments.

Speaker: Thomas B Clegg (University of North Carolina-Chapel Hill and Triangle Universities Nuclear Laboratory)

Clegg-SPIN 2023 Talk-Final.pptx

255 Status of the Electron-Ion Collider

The Electron-Ion Collider is gearing up for "Critical Decision 2", the project baseline with defined scope, cost and schedule. Lattice designs are being finalized, and preliminary component design is being carried out. Beam dynamics studies such as dynamic aperture optimization, instability and polarization studies, and beam-beam simulations are continuing in parallel. We report on the latest developments and the overall status of the project, and present the plans for future activities.

Speaker: Christoph Montag (BNL)

Status of the EIC - Montag (2).pptx

256 New Opportunities with Jefferson Lab at 22 GeV

The CEBAF accelerator at Jefferson Lan delivers the world’s highest intensity multi-GeV electron beams. The 12 GeV era at the laboratory is well underway, with many important experimental results already published and approved experiments planned for the next decade. At the same time, the CEBAF community is looking toward its future and the science that could be obtained through a cost-effective upgrade to 22 GeV. The potential to upgrade CEBAF to higher energies opens a rich and unique experimental nuclear physics program - with spin observables a major focus. A brief overview of the upgrade plans will be presented, along with some of the motivating science that explores different facets of non-perturbative dynamics manifested in hadron structure and the richness of strongly interacting systems.

Speaker: Dr Cynthia Keppel (Jefferson Lab)

SPIN2023_Keppel.pdf

SPIN2023_Keppel.pptx

257 ISPC Report

Speaker: Paolo Lenisa (University of Ferrara and INFN)

LENISA_SPIN2023.pdf

258 Closeout

Speakers: Anselm Vossen (Duke University/JLab), Thomas Mehen (Duke U.), Thomas Mehen (Duke University)