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,...
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...
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 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,...
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...
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...
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...
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 $\Lambda$...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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.
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...
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...
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...
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...
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...
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...
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.
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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 ($p^{\uparrow}+A$)....
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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.
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
{\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$\overline{c}$...
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...
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.
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...
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...
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...
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...
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...
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...
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...
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...
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...
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,...
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...
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...
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...
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....
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...
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...
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...
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...
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...
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...
We compute the gravitational form factors of various nuclei in the Skyrme model. Based on https://arxiv.org/abs/2304.05994
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...
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...
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...
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...
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...
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...
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....
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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-$x$,...
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...
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...
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.
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...
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...
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...
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...
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...
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.
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...
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...
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...
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...
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...
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...
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...
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...
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,...
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...
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...
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...
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.
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...
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...
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...
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...
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...
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...
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...
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....
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...
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...
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...
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...
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
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...
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...
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...
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...
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.
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...
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...
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...
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...
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...
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,...
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...
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...
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...
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...
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...
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....
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...
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...
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...
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.
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...
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...
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...
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...
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.
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...
We present ongoing studies and some future
measurements with hadrons in electroproduction at Jefferson Lab
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...
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...
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....
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...
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.
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...
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...
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...
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.
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...
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]...
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...
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
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...
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...
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...
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...
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),...
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...
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...
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.
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...
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...
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...
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...
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...
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...
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.
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...
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...
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...
Diquark bonds formed with valence quarks from two different nucleons have been proposed as the fundamental quantum chromodynamics (QCD) physics causing short-range correlations (SRC) in nuclei. The 12-quark "hexadiquark" hidden-color QCD state - effectively two SRC bound together - is also proposed as the cause of distortions of quark distribution functions in nuclei. While SRC have been...
Hard Exclusive Meson Production (HEMP) and Deeply Virtual Compton Scattering (DVCS) are very promising reactions to access Generalized Parton Distributions (GPDs). Such exclusive measurements were performed at COMPASS in 2016 and 2017 at the M2 beamline of the CERN SPS using the 160 GeV muon beam scattering off a 2.5 m long liquid hydrogen target surrounded by a barrel-shaped time-of-flight...
Level anticrossings (LACs) occur in diverse quantum systems and underpin a plethora of fascinating phenomena. Of particular interest here is the role of LACs in inducing nuclear spin hyperpolarization for sensitivity-enhanced nuclear magnetic resonance (NMR) spectroscopy and imaging. Theoretical and experimental manifestations of LACs in nuclear spin systems incorporating protons from...
In this talk I will present our extraction of the two scalar and four spin leading-order proton polarizabilities.
I will review the bootstrap method that allowed us to incorporate in a natural way the systematic errors on the experimental data and that allowed for many different consistency checks. I will then briefly discuss the used database, and present the final result.
STAR collaboration observed a global spin alignment of $\phi$-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...
Solid-state systems featuring optically polarizable electrons present intriguing possibilities due to the potential for local injection of spin polarization into neighboring nuclear spins. This process results in the enhancement of their magnetic resonance signatures by several orders of magnitude. In this talk, I will discuss the fascinating opportunities arising from these "hyperpolarized"...
The light meson spectrum is explored with the GlueX experiment at Jefferson Lab using a real photon beam with energies of up to 12 GeV. At these high energies, the dominant meson photoproduction mechanism in forward direction is the exchange of Reggeons. Understanding the production mechanism is essential for ongoing searches of exotic hybrid mesons in the meson spectrum. An important...
In this talk I will present the factorization theorem at next-to-leading power accuracy for quasi-TMD distributions.
I will discuss on the one side the applications and limitations of such factorization theorem and on the other side the theoretical significance of it as the first complete and explicit example of emergence and cancellation of the `special' rapidity divergences.
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...
There exists an unresolved discrepancy regarding calculations of two-baryon interactions from lattice QCD. This difference initially began as a disagreement between two very different methods (i.e. Lüscher’s two-particle quantization condition and the HAL QCD potential method), leading to questions regarding the control over systematics within each method. For instance, Lüscher’s quantization...
We initiate the study of transverse momentum-dependent (TMD) fragmentation functions for heavy quarks, demonstrate their factorization in terms of novel nonperturbative matrix elements in heavy-quark effective theory (HQET), and prove new TMD sum rules that arise from heavy-quark spin symmetry. We discuss the phenomenology of heavy-quark TMD FFs at $B$ factories and find that the Collins...
