Conveners
3D Structure of the Nucleon: TMDs: TMDs I
- Yoshitaka Hatta (Brookhaven National Laboratory)
3D Structure of the Nucleon: TMDs: TMDs II
- Andreas Metz (Physics Department, Temple University, Philadelphia)
3D Structure of the Nucleon: TMDs: TMDs III
- Andrea Signori (University of Turin and INFN)
3D Structure of the Nucleon: TMDs: TMDs IV
- Leonard Gamberg (Penn State Berks)
3D Structure of the Nucleon: TMDs: TMDs V
- Michael Engelhardt (NMSU)
3D Structure of the Nucleon: TMDs: TMDs VI
- Alessandro Bacchetta (University of Pavia and INFN Pavia)
3D Structure of the Nucleon: TMDs: TMDs VII
- Tommaso Rainaldi (Old Dominion University)
3D Structure of the Nucleon: TMDs: TMDs VIII
- Daniel Pitonyak (Lebanon Valley College)
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...
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...
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...
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...
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...
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.
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...
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...
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...
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 ($p^{\uparrow}+A$)....
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...
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...
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...
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...
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...
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...
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.
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...
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...
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...
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...
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....
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...
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...
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...
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...
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.
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...
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.
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...
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...
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 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...
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 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...
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...
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...
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...
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...
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...
We present theoretical estimates of azimuthal asymmetries in back-to-back production of D meson and a jet in eP collision in the kinematics of the upcoming electron-ion collider (EIC). We consider two cases, when the proton is unpolarized, and also when the proton is transversely polarized. We show that these asymmetries can probe different gluon TMDs in a wide kinematical region.
