Keynote speech: Evolution of studies of the spin structure of the proton

• Toshiaki Shibata (Nihon University/Tokyo Institute of Technology)

Room: Cypress Room (翠海厅) The talk consists of two parts. Spending the first several minutes, I will talk on ‘Evolution of the PacificSpin Symposium on High Energy Spin Physics’. This symposium was started in Kobe in Japan in 1996. It was only several years after the EMC’s result[1,2] on the proton spin came out. It was before the RHIC experiments started. The aim of the symposium is to further enhance high energy spin physics in the circum-pan-Pacific region. In this symposium, we consider it important 1) to provide sufficient time for discussions among the participants, and 2) to encourage young physicists to participate. In the rest of the time, I will talk on ‘Evolution of studies of the spin structure of the proton’. The spin structure of the proton has been studied for many years, and the studies are now divided into a few domains. I present an overview of the evolution. The concept of ‘spin’ was introduced in 1920’s. Spin has been a key element in physics since then. Fermions with spin 1/2 are described as spinors. Spinors have specific properties which are different from vectors and scalars. After the pioneering experiments of polarized deep inelastic scattering (DIS) at SLAC, longitudinally polarized muon beams became available at high energy proton accelerators. Thus, the beam energy increased about 10 times. As the result, the accessible kinematic region in DIS was extended to the small Bjorken-x region. EMC group, using the muon beam up to 200 GeV, reported in 1988 and 1989 [1,2] that the contributions of spins of quarks and anti-quarks to the proton spin are small. The amount of the contributions reported in their 1989 paper was (12 ± 9 ± 14)%. This result motivated many experimental and theoretical studies afterwards. The spin sum rule 1/2 = 1/2 ΔΣ + ΔG + Lq,¯q + LG suggests the possible contributions from other parts. Here, the right hand side of the equation has terms representing contributions of spins of quarks and anti-quarks, spins of gluons, orbital angular momenta of quarks and anti-quarks and of gluons. As the theoretical framework, the parton model and the scaling property in DIS were proposed in 1960’s. The asymptotic freedom was theoretically discovered in 1973 and QCD was established as a field theory. The factorization theorem was important to interpret DIS and hadron reactions. Scaling violation (Q2-dependence) of the parton distributions and the QCD evolution equation were essential for the developments of this field. The perturbative QCD and the lattice QCD calculations are two approaches to the proton structure. The transverse single-spin asymmetry had been observed in hadron reactions since many decades. The asymmetry was also observed in DIS about 20 years ago. The analyses in the context of transverse-momentum-dependent parton distributions opened a new aspect of the studies of the parton structure of the proton. It became also possible to observe exclusive productions of photons and mesons in lepton scattering. The generalized parton distributions led to the studies of 3D structure of the proton. The contributions of orbital angular momenta of quarks, antiquarks and gluon could be crucial. Polarized p-p reaction program at the collider RHIC added new insights to the proton spin structure, in particular to the gluon spin contribution. EIC (Electron-Ion-Collider)[3] now in preparation will be the first collider experiments with polarized electron and polarized light ions. The evolution of the studies of the spin structure of the proton will continue with novel experimental technique and advanced theory. [1] J. Ashman et al., EMC, Phys. Lett. B206 (1988) 364. [2] J. Ashman et al., EMC, Nucl. Phys. B328 (1989) 1. [3] R. Abdul Khalek et al., EIC Yellow Report, Nucl. Phys. A1026 (2022) 122447.

EIC experiment

• Yuji Goto

Room: Cypress Room (翠海厅)

Precision studies of the DVCS process at JLab

• Julie Roche (Ohio University)

Room: Cypress Room (翠海厅) Generalized Parton Distributions (GPDs) describe the correlation between the spatial distribution of the quarks and its longitudinal momentum fraction. Their definition in the mid-1990s has revolutionized our approach to the description of the internal structure of the nucleon. The study of the GPDs is at the forefront of today’s hadronic physics enterprise. Deeply Virtual Compton Scattering (DVCS) off the nucleon ($\gamma^* N \rightarrow \gamma N $) is the simplest process sensitive to the GPDs. It has been measured at Hera, Compass, and JLab. In this talk, I will review the results of the Hall A-C @ JLab scheme. In these experiments, an EM calorimeter is used in coincidence with a well-known high-resolution spectrometer. This relatively simple scheme allows for precise (~ 5%) measurements of absolute beam polarized and unpolarized cross-sections essential for studying GPDS. I will show DVCS results off proton and neutrons target as well as results on exclusive pion production of those same targets.

LHCspin: a polarized fixed-target experiment at the LHC

• Luciano Libero Pappalardo (University of Ferrara, Italy)

Room: Cypress Room (翠海厅) A polarized gaseous target, operated in combination with the high-energy and high-intensity LHC beams, has the potential to open new physics frontiers and to deepen our understanding of the strong interaction in the non-perturbative regime of QCD. Specifically, the LHCspin project aims to perform spin-physics studies in high-energy polarized fixed-target collisions using the LHCb detector. Being designed and optimized for the detection of heavy hadrons, LHCb will allow to probe the nucleon structure through, e.g., the inclusive production of c- and b-hadrons, and ideal tool to access the essentially unexplored spin-dependent gluon TMDs. This configuration will allow to explore the nucleon internal dynamics at unique kinematic conditions, including the poorly explored high x-Bjorken and high x-Feynman regimes. With the installation of the proposed setup, LHCb will become the first experiment delivering simultaneously unpolarized beam-beam collisions at 14 TeV and both polarized and unpolarized beam-target collisions at center-of-mass energies of the order of 100 GeV. The status of the LHCspin project is presented along with a selection of physics opportunities.

Puzzle for the Vector Meson Threshold Photoproduction

• Igor Strakovsky (The George Washington University)

Room: Cypress Room (翠海厅) High-statistics total cross sections for the vector meson photoproduction at the threshold: $\gamma p\to \omega p$ (from A2 at MAMI and ELPH), $\gamma p\to \phi p$ (from CLAS6 at JLab) and $\gamma p\to J/\psi p$ (from GlueX at JLab) allow one to extract the absolute value of vector meson nucleon scattering length using Vector Meson Dominance (VMD) model. The ``young’’ vector meson hypothesis may explain the fact that the obtained scattering length value for the nucleon $\phi$-meson compared to the typical hadron size of approximately $1~\mathrm{fm}$ indicates that the proton is more transparent for the $\phi$-meson compared to the $\omega$-meson and is much less transparent than the $J/\psi$-meson. The extended analysis of $\Upsilon$-meson photoproduction using quasi-data from the QCD approach is in perfect agreement with the light-meson findings using experimental data. Recent high-statistical $J/\psi$ photoproduction cross sections measured by the GlueX Collaboration allow us to search for the exotic $P_c(4312)$ state observed by the LHCb Collaboration. The fits show that destructive interference involving a $S$ wave resonance and associated nonresonance background produces a sharp dip structure approximately $77~\mathrm{MeV}$ below the LHCb mass, in the same location as a similar structure is seen in the data. The interference between open charm and gluon exchange may (by some accident) produce a dip, but there is room for resonance. Future high-quality experiments by EIC and EicC will have the opportunity to evaluate cases for $J/\psi$- and $\Upsilon$-mesons. It allows us to understand the dynamics of $c\bar{c}$ and $b\bar{b}$ production at the threshold and to look for the effect of LHCb $P_c(4312)$. The ability of J-PARC to measure $\pi^-p\to \phi n$ and $\pi^-p\to J/\psi n$, which are free from the VMD model, is evaluated.

Prospects on GPDs and gravitational form factors of hadrons

• Shunzo Kumano (Japan Women's University / KEK)

Room: Cypress Room (翠海厅) Masses and spins of hadrons are fundamental quantities in physics; however, their origins are not understood yet and their investigations are major purposes of building electron-ion colliders in 2030's. Both of them can be investigated by generalized parton distributions (GPDs). The spacelike (timelike) GPDs are studied by deeply virtual Compton scattering (two-photon processes) at charged-lepton accelerator facilities ($e^+ e^-$ collider facilities) such as the JLab, CERN-AMBER, and EICs (KEKB). I discuss experimental prospects mainly at the $e^+ e^-$ collider KEKB, the hadron-accelerator facility J-PARC, and the Long-Baseline Neutrino Facility (LBNF) at Fermilab. It is possible to extract the timelike GPDs and gravitational form factors of hadrons by the two-photon processes $\gamma^* + \gamma \to h + \bar h$, where h is a hadron. Actually, there was the first report on the determination of the gravitational form factors and radii (mass and mechanical radii were 0.32-0.39 fm and 0.82-0.88 fm for $\pi^0$) from actual experimental measurements in Ref.[1]. At J-PARC, the GPDs will be investigated by the exclusive Drell-Yan process $\pi^- p \to \mu^+ \mu^- B$ [2], where the baryon B could be a nucleon or $\Delta$. In future, other processes could be investigated for the GPDs. For example, the $2 \to 3$ reaction processes $NN \to N \pi B$ could be used for probing the GPDs in the ERBL (Efremov-Radyushkin-Brodsky-Lepage) region. In addition, the neutrino facility Fermilab-LBNF, possibly also the nuSTORM at CERN, can be used for the GPD measurement by the single-pion production processes $\nu + N \to \ell^- + N' + \pi$ and $\bar\nu + N \to \ell^+ + N' + \pi$ [3]. References [1] S. Kumano, Qin-Tao Song, and O. V. Teryaev, Phys. Rev. D 97, 014020 (2018). [2] S. Kumano, M. Strikman, and K. Sudoh, Phys. Rev. D 80, 074003 (2009), T. Sawada *et al*., Phys. Rev. D 93, 114034 (2016); J-K. Ahn *et al*., Letter of Intent for J-PARC, LoI_2019-07; Wen-Chen Chang *et al*., J-PARC proposal under preparation. [3] X. Chen, S. Kumano, R. Kunitomo, S. Wu, and Y.-P. Xie, arXiv:2401.11440, European Physical Journal A, in press.

QCD relations on gravitational form factors

• Kazuhiro Tanaka (Juntendo Univ.)

Room: Cypress Room (翠海厅)

Origin of hadron spin based on Lattice QCD study on the charmed hadrons

• Yi-Bo Yang (ITP-CAS)

Room: Cypress Room (翠海厅) We perform the first Lattice calculation about the charmed hadron spin decomposition using overlap fermions on a 2+1 flavor RBC/UKQCD domain-wall gauge configurations at 0.083 fm with 300~MeV pion mass. It is found that the contributions of quark spin to the spin of 1S, 1P charmonia and also proton-like triple heavy quark state are comparable with the expectation of non-relativistic quark model. \red{Such an observation provides evidence that the non-triviality of proton spin decomposition mainly arises from the relativistic effects of the light quark. Conversely, the substantial gluon angular momentum contribution in the spin $(1/2)^+$ state with triple heavy quarks with the charm quark mass, remains significant, highlighting the ongoing importance of the gluon in the realm of charmed baryon physics.

GPDs of nucleon and meson in a light-cone model

• Zhun Lyu

Room: Cypress Room (翠海厅)

Radiative Correction to Spin Polarization in Off-equilibrium Medium

• Shu Lin

Room: Cypress Room (翠海厅)

Global analysis of fragmentation functions with high-precision data from the LHC

• Jun Gao

Room: Cypress Room (翠海厅)

TBD

• Xiang-dong Ji

Room: Cypress Room (翠海厅)

Global polarization experiments: past, present and future

• Jin-hui Chen

Room: Cypress Room (翠海厅)

Theoretical progress on spin polarization in heavy ion collisions

• Xu-Guang Huang

Room: Cypress Room (翠海厅)

Helicity polarization in heavy ion collisions at RHIC-BES energies

• Di-Lun Yang (Academia Sinica)

Room: Cypress Room (翠海厅) In relativistic heavy ion collisions (HIC), strong vorticity can be generated for the produced quark gluon plasmas, which could lead to spin polarization of quarks and gluons inherited by the spin polarization of Lambda hyperons measured by the weak decay. Nevertheless, to understand the local distribution of vortical fields, the local spin polarization along the beam direction with the azimuthal angle dependence was further measured. It is however found that there exist various contributions from other sources such as the shear strength or chemical-potential gradients for local spin polarization on top of the vortical effect. In order to probe the local structure of vortical fields and obtain a baseline for additional corrections in and out of equilibrium on top of the vorticity, we investigate the hydrodynamic helicity polarization of Lambda hyperons, defined as the projection of the spin polarization vector along the directions of particle momenta, at RHIC-beam-energy-scan (BES) energies by utilizing the relativistic (3+1) dimensional viscous hydrodynamics framework with prescribed initial conditions. As opposed to local spin polarization at high energy collisions, our hydrodynamic simulations demonstrate that the helicity polarization induced by the kinetic vorticity dominates over other contributions at intermediate and low collision energies. Our findings hence provide an opportunity to probe the fine structure of local kinetic vorticity as a function of azimuthal angle at intermediate and low collision energies by mapping our predictions to the future measurements in experiments.

Spin physics at small-x

• Jian Zhou

Room: Cypress Room (翠海厅) In this presentation, I will review recent developments in spin physics at small 𝑥, focusing on three main topics: the linear polarization of gluons, the spin-dependent odderon, and the small-x evolution of gluon orbital angular momentum. Additionally, I will discuss the prospects for exploring nucleon spin structure at the future EIC.

RHIC spin program

• Jinlong Zhang (Shandong University)

Room: Cypress Room (翠海厅) As the first and only high-energy polarized proton-proton collider in the world, RHIC (Relativistic Heavy Ion Collider) has provided unique opportunities for experimental studies of the nucleon spin structure. The featured measurements include direct access to the gluon helicity, flavor-separated sea-quark helicity, and rich transverse spin effects. The recent STAR forward upgrades and newly commissioned sPHENIX with significantly enlarged detector acceptance will further unleash the potential of the polarized proton-proton collisions, especially on precision measurements of transverse spin asymmetries. In this presentation, a brief review, selected recent results, and an outlook of the RHIC spin program will be discussed.

Exploring nucleon TMDs and GPDs by the Drell-Yan process

• Wen-Chen Chang (Institute of Physics, Academia Sinica)

Room: Cypress Room (翠海厅) The nucleon spin structure has been understood by nucleon TMDs and GPDs. Conventionally, TMDs and GPDs are obtained from, for example, the SIDIS and DVCS processes utilizing lepton beams. A complementary approach is the measurement of (un)polarized Drell-Yan processes with hadron beams. The universality properties of nucleon TMDs and GPDs determined in space-like and time-like experimental approaches could be checked. In this talk, we will discuss the recent results of nucleon Sivers, transversality, and Boer-Mulders TSAs measured by the COMPASS experiment, and sketch the plan for measuring nucleon GPDs by the exclusive pion-induced Drell-Yan process at J-PARC.

SpinQuest: Investigating sea quark and gluon Sivers effects in the nucleon

• Stephen Pate (New Mexico State University, Las Cruces NM 88003, USA)

Room: Cypress Room (翠海厅) SpinQuest is a polarized fixed-target Drell-Yan experiment at Fermi National Accelerator Laboratory, utilizing a 120 GeV proton beam incident upon transversely polarized NH$_3$ and ND$_3$ targets. The primary goal of the experiment is the determination of the $\bar{u}$ and $\bar{d}$ contribution to a single-spin azimuthal asymmetry in the production of virtual photons in the invariant mass range $4<M<8$ GeV. This asymmetry, called the Sivers asymmetry, arises from a spin-momentum correlation between the transverse momentum $\vec{k}_T$ of a parton and the spin axis $\vec{S}$ of the nucleon. A non-zero $\bar{u}$ and/or $\bar{d}$ Sivers asymmetry implies a non-zero orbital angular momentum of the $\bar{u}$ and/or $\bar{d}$ quarks. Non-zero Sivers asymmetries have already been observed for valence quarks in leptonic deep-inelastic scattering at HERMES and COMPASS. In addition to this fundamental measurement in nucleon spin physics, we will also observe the transverse single-spin asymmetry in the production of $J/\psi$ particles, which is sensitive to the gluon Sivers function. Additionally, observing a sign change in the light quark sea Sivers asymmetry between this measurement and future deep-inelastic measurements at the Electron-Ion Collider would be a test of a fundamental prediction of Quantum Chromodynamics. In this presentation I will review the physics and technology underpinning the experiment.

Extraction of pion and kaon PDFs from Drell-Yan and charmonium production data in the statistical model

• JEN CHIEH PENG (University of Illinois at Urbana-Champaign)

Room: Cypress Room (翠海厅) We present an analysis to extract pion and kaon parton distribution functions (PDFs) using meson-induced Drell-Yan and charmonium production data. Starting from the statistical model first developed for determining the partonic structure of spin-1/2 nucleon and later applied to the spin-0 mesons, we have extended this approach to perform a global fit to existing pion- and kaon-induced Drell-Yan and 𝐽∕𝜓 production data. These data are well described by the statistical model, allowing an extraction of the pion and kaon PDFs. We find that both the Drell-Yan and the 𝐽∕𝜓 data favor a harder valence distribution for strange quark than for up quark in kaon. The pion and kaon gluon distributions are further constrained by the 𝐽∕𝜓 production data. In particular, the momentum fraction carried by gluons is found to be similar for pion and kaon. This work is based on collaboration with Claude Bourrely, Franco Buccella, and Wen-Chen Chang.

Compass SIDIS

• Andrea Bressan

Room: Cypress Room (翠海厅)

GPD Measurement at the COMPASS Experiment

• Po-Ju Lin (National Central University)

Room: Cypress Room (翠海厅) Generalized Parton Distributions (GPDs) are one of the approaches that address the beyond-one-dimensional partonic structure of the proton. With GPDs, interesting insights into the properties of a proton can be gained. Utilizing the polarized muon beam provided by the M2 beam line at CERN SPS, COMPASS has conducted measurements of DVCS and the exclusive production of various mesons for the study of GPDs. In this presentation, a collection of results on exclusive measurements from COMPASS will be presented.

Proton spin decomposition from a light-front Hamiltonian approach

• Xingbo Zhao (Institute of Modern Physics, Chinese Academy of Sciences)

Room: Cypress Room (翠海厅) I will report our recent progress in studying the structure of the proton in a nonperturbative approach in the light-front Hamiltonian formalism named Basis Light-front Quantization. In this approach we investigate the structure of the proton through solving the eigenvalue problem of the light-front Hamiltonian of QCD. With the obtained eigenvector (light-front wave function) we calculate the generalized parton distributions and generalized transverse-momentum-dependent parton distructions of the proton, which provide the information of the spin decomposition among the valence quarks, the gluons and the sea quarks.

Constraining the collision terms in spin kinetic theory

• Jian-hua Gao

Room: Cypress Room (翠海厅) We derive self-consistent constraint conditions for collision terms in spin kinetic theory within Wigner function formalism. With these constraint conditions, we propose some simple specific collisions terms. Especially, we discuss the spin kinetic theory at relaxation-time approximation and spin polarization effects in relativistic heavy-ion collisions.

Transverse spin asymmetry as a probe of new physics beyond the SM

• Yan Bin (IHEP)

Room: Cypress Room (翠海厅) The absence of signals for new heavy resonances at the Large Hadron Collider (LHC) suggests that the scale of new physics (NP) likely significantly exceeds the electroweak scale. The Standard Model Effective Field Theory (SMEFT) has become a valuable framework for systematically capturing potential NP effects, with leading contributions expected from dim-6 operators. However, chirality-flipping dim-6 operators for light fermions, which are poorly constrained as their interference with the SM will be highly suppressed. In this talk, I will discuss recent progress in exploring these NP effects through transverse polarization effects without such suppression, and it also offering a new avenue to investigate potential CP violation effects.

New insight into the structure of baryon excited states

• Anthony W. Thomas

Room: Cypress Room (翠海厅)

J-PARC

• Shinya Sawada

Room: Cypress Room (翠海厅)

The SPD project at NICA.

• Alexey Guskov (Joint Institute for Nuclear Research, Dubna)

Room: Cypress Room (翠海厅) The Spin Physics Detector (SPD) is a universal detector in the one of two interaction points of the NICA collider under construction at JINR, Dubna. SPD plans to study the spin structure of the proton and deuteron and other spin-related phenomena using a unique possibility to operate with polarized proton and deuteron beams at a collision energy up to 27 GeV and a luminosity up to $10^{32}$ cm$^{-2}$ s$^{-1}$. As the main goal, the experiment aims to provide access to the gluon TMD PDFs in the proton and deuteron, as well as the gluon transversity distribution and tensor PDFs in the deuteron, via the measurement of specific single and double spin asymmetries using different complementary probes such as charmonia, open charm, and prompt photon production processes. Other polarized and unpolarized physics is possible, especially at the first stage of NICA operation with reduced luminosity and collision energy of the proton and ion beams. Construction of the first stage of the SPD facility is included in the JINR seven-year development plan for 2024-2030. The physics program of the SPD project and the design of the SPD setup will be presented.

Experimental study of fragmentation functions at BESIII and STCF

• Yateng ZHANG (ZZU)

Room: Cypress Room (翠海厅) Fragmentation Function (FF) plays a crucial role in describing the hadronization process. We report the measurements of normalized differential cross sections of inclusive hadrons production, including pi0, Ks and eta, as a function of hadron momentum at six energy points with q^2 transfer from 5 to 13 GeV^2 at BESIII. The results with a relative hadron energy coverage from 0.1 to 0.9 are compared with several theoretical calculations based on existing fragmentation functions. Finally，Lastly, we look forward to future research on Fragmentation Functions at STCF.

Fragmentation functions from Belle I & Belle II

• Simon Schneider

Room: Cypress Room (翠海厅)

Electron-Ion Collider in China (EicC)

• Yuxiang Zhao (Institute of Modern Physics)

Room: Cypress Room (翠海厅) Studying the origin of nucleon spin and mass in Quantum Chromodynamics (QCD) is essential for understanding the fundamental constituents of visible matter and the underlying strong force that governs their interactions. The Electron-ion collider in China (EicC) has been proposed to carry out dedicated research to explore these open questions. The EicC will feature highly polarized electrons (with a polarization of ∼80%) colliding with protons (with a polarization of ∼70%) at the variable center of mass energies ranging from 15 to 20 GeV and a luminosity of (2-4) × 10$^{33}$cm$^{−2}$s$^{−1}$. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will also be available. The EicC team is working on the conceptual design report which will be relased in the end of 2024. This talk will outline the scientific objectives of the EicC, the experimental capabilities it will offer, and the corresponding detector systems planned for the facility.

Generalized parton distributions of spin-3/2 particles

• Yubing Dong

Room: Cypress Room (翠海厅)

QCD sum rules for hadron spin decomposition

• Hyungjoo Kim (Hiroshima University)

Room: Cypress Room (翠海厅)

Lambda polarization in deep inelastic scattering

• Tianbo Liu (Shandong University)

Room: Cypress Room (翠海厅) Deep inelastic scattering is an established approach to study nucleon structures. Owing to the self-analyzing weak decay, the $\Lambda$ production in DIS and its polarization are expected as sensitive observables to the spin structure of the strange sea. In this talk, we will demonstrate the importance to understand the origin or the hadronization mechanism of the $\Lambda$ production, and propose to take advantage of spin as a powerful probe. We find that the spin transfer can be significantly suppressed by the target fragmentation mechanism. With this effect taken into account, experimental data can be well described, which alleviates the tension between data and current fragmentation predictions, offering a new perspective to explore the hadronization mechanism in DIS.

Parton distribnution functions in tensor-polarized spin-1 hadrons

• Qintao SONG (Zhengzhou University)

Room: Cypress Room (翠海厅) The study of the tensor-polarized structures can help us reveal the internal structure of spin-1 hadrons. For example, the spin-1 deuteron is often considered as a loosely bound system of proton and neutron, and this is known as the standard model of the deuteron. In 2005, the HERMES collaboration measured the tensor-polarized PDF $f_{1LL}$ of the deuteron, but the experimental results are significantly larger than the theoretical predictions based on the standard model. This may suggest that there could be non-nucleonic structures in deuteron. To solve this puzzle, the tensor-polarized PDFs of deuteron will be accurately measured at Jefferson Lab and Fermilab in the United States, and at NICA in Russia. In this presentation, we focus on the tensor-polarized PDFs, FFs, and TMDs of spin-1 hadrons. We present theoretical relations between these distributions, which should be helpful for the future extraction of tensor-polarized distributions from experimental measurements. In addition, the higher twist corrections are also discussed for the reactions where spin-1 hardons are involved.

Current status of the theoretical study on the single spin asymmetry and prospects at the future experiment

• Shinsuke Yoshida (South China Normal University)

Room: Cypress Room (翠海厅) The single transverse-spin asymmetry(SSA) was first accepted as a mystery in QCD when it was observed in the late 70s. Half a century has passed since then, the SSA is now attracting attention as a tool for revealing new aspects of the nucleon structure. The understanding of the 3-dimensional structure through the SSA study is one of the main goals of the future electron-ion collider(EIC) experiment. In this talk, I will introduce some important theoretical developments made in the past couple of decades and some interesting discussions on the EIC experiment.

PDF on lattice

• peng sun (Institute of Modern Physics, Chinese Academy of Sciences)

Room: Cypress Room (翠海厅)