The 12th Circum-Pan-Pacific Symposium on High Energy Spin Physics

Nov 8, 2024, 2:00 PM → Nov 13, 2024, 12:00 PM Asia/Shanghai

Cypress Room (翠海厅) (Hefei Crowne Plaza )

Qun Wang (University of Science and Technology of China)

The 12th Circum-Pan-Pacific Symposium on High Energy Spin Physics, PacificSpin2024, will take place between November 9 to November 12, 2024. The on-site registration is on November 8, 2024. The Symposium venue is Hefei Crowne Plaza (安徽合肥皇冠假日酒店，黄山路598号A座), China.

The indico page of the symposium is https://indico.pnp.ustc.edu.cn/e/PacificSpin2024

This Symposium aims to enhance communications among physicists from the Circum-Pan-Pacific region and other regions. Participation of young physicists in this Symposium is strongly encouraged. Symposia in this series took place in Miyazaki(2019), Taipei(2015), Ji'nan(2013), Cairns(2011), Yamagata(2009), Vancouver(2007), Tokyo(2005), Washington(2003), Beijing(2001), Wako(1999), and Kobe (1996).

The symposium mainly consists of plenary sessions. The idea is that all participants share the same discussions and deepen the common understanding of current problems and perspectives. The slides of the talks will be archived and made public. 

PacificSpin 2024 will be jointly hosted by Anhui University of Science & Technology (AUST) and University of Science and Technology of China (USTC), sponsored by University of Chinese Academy of Sciences (UCAS), Peking University (PKU), Shandong University (SDU).

On-site registration: 

• Date and time: 14:00 - 18:00, November 8, 2024 (2024年11月8日下午14:00-18:00)
• Location: registration desk at the lobby lounge of Crowne Plaza (皇冠假日酒店大厅注册处)

Important dates

• Deadline for early registration with reduced registration fee: September 15, 2024
• Abstract submission for contributed talks will be closed on September 30, 2024
• Registration date: November 8, 2024
• Program dates: November 9 - 12, 2024

Circulars

June 4: first circular 

October 15: timetable 

November 2: second circular

Contact

E-mail address:PacificSpin2024@gmail.com

1st Circular_of_PacificSpin2024.pdf

2nd Circular of PacificSpin2024.pdf

Destinations.pdf

Overview of the timetable

PacificSpin2024_handbook_v3.pdf

PacificSpin2024_poster.jpg

PacificSpin_poster_horizontal.jpg

Friday, November 8

2:00 PM → 6:00 PM Registration

On-site registration

7:00 PM → 9:00 PM Dinner

Saturday, November 9

8:30 AM → 8:45 AM Symposium Opening

Welcome remark from Academician Yuan Liang, President of Anhui University of Science and Technology

Speaker: Liang Yuan (Anhui University of Science and Technology)

8:45 AM → 10:00 AM Plenary: Nov 9, morning 1

Convener: Qun Wang (University of Science and Technology of China)

8:45 AM Keynote speech: Evolution of studies of the spin structure of the proton

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.

Speaker: Toshiaki Shibata (Nihon University/Tokyo Institute of Technology)

1_Shibata-PacificSpin2024.pdf

9:25 AM EIC experiment

Speaker: Yuji Goto

Goto_PacSpin2024.pdf

10:00 AM → 10:15 AM Group photo

10:15 AM → 10:30 AM Coffee break

10:30 AM → 12:15 PM Plenary: Nov 9, morning 2

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

10:30 AM Precision studies of the DVCS process at JLab

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.

Speaker: Julie Roche (Ohio University)

2024_DVCS_HEIFEI_Roche.pdf

2024_DVCS_HEIFEI_Roche.pptx

11:05 AM LHCspin: a polarized fixed-target experiment at the LHC

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.

Speaker: Prof. Luciano Libero Pappalardo (University of Ferrara, Italy)

Pappalardo_PacificSpin2024.pdf

11:40 AM RHIC spin program

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.

Speaker: Jinlong Zhang (Shandong University)

RHIC_SPIN_JLZhang.pdf

12:15 PM → 2:00 PM Lunch break

2:00 PM → 3:45 PM Plenary: Nov 9, afternoon 1

Convener: Yuji Goto

2:00 PM Prospects on GPDs and gravitational form factors of hadrons

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.

Speaker: Shunzo Kumano (Japan Women's University / KEK)

Pacific-spin-2024-11-v2.pdf

2:35 PM QCD relations on gravitational form factors

Speaker: Kazuhiro Tanaka (Juntendo Univ.)

pacspin24_11_09_v2.pdf

3:10 PM Origin of hadron spin based on Lattice QCD study on the charmed hadrons

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.

Speaker: Yi-Bo Yang (ITP-CAS)

2024.11.09.pdf

3:45 PM → 4:00 PM Coffee break

4:00 PM → 5:45 PM Plenary: Nov 9, afternoon 2

Convener: Xin-Nian Wang

4:00 PM GPDs of nucleon and meson in a light-cone model

Speaker: Zhun Lyu

GPDs_Zhun_Lu.pptx

4:35 PM Radiative Correction to Spin Polarization in Off-equilibrium Medium

Speaker: Shu Lin

5_spin_symposium_Shu_Lin.pdf

5:10 PM Global analysis of fragmentation functions with high-precision data from the LHC

Speaker: Jun Gao

hefei2024.pdf

5:45 PM → 6:15 PM Free discussion (Chair: T. Shibata)

7:00 PM → 9:00 PM Welcome Reception

Sunday, November 10

8:30 AM → 10:15 AM Plenary: Nov 10, morning 1

Convener: Zuo-Tang Liang

8:30 AM How difficulty is it to verify spin sum rules experimentally

Speaker: Xiang-dong Ji

test_spin_sum_rule.pptx

9:05 AM Global polarization experiments: past, present and future

Speaker: Jin-hui Chen

2_Spin-polarization-HIC-Exp-Chen.pdf

9:40 AM Theoretical progress on spin polarization in heavy ion collisions

Speaker: Xu-Guang Huang

3_X.G.Huang-2024.11.10.pdf

10:15 AM → 10:30 AM Coffee break

10:30 AM → 12:15 PM Plenary: Nov 10, morning 2

Convener: Shunzo Kumano (Japan Women's University / KEK)

10:30 AM Helicity polarization in heavy ion collisions at RHIC-BES energies

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.

Speaker: Di-Lun Yang (Academia Sinica)

Helicity_pol_Hefei.pdf

11:05 AM Spin physics at small-x

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.

Speaker: Jian Zhou

合肥spin.pdf

11:40 AM Puzzle for the Vector Meson Threshold Photoproduction

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.

Speaker: Igor Strakovsky (The George Washington University)

Pan-Pacific_Symposium_2024_Igor.pdf

12:15 PM → 2:00 PM Lunch break

2:00 PM → 6:00 PM Free discussion

7:00 PM → 9:00 PM Banquet

Monday, November 11

8:30 AM → 10:15 AM Plenary: Nov 11, morning 1

Convener: Anthony W. Thomas

8:30 AM Exploring nucleon TMDs and GPDs by the Drell-Yan process

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.

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

PacificSPIN2024_wchang.pdf

9:05 AM SpinQuest: Investigating sea quark and gluon Sivers effects in the nucleon

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

Speaker: Prof. Stephen Pate (New Mexico State University, Las Cruces NM 88003, USA)

SFP_PacificSpin2024_SpinQuest.pdf

9:40 AM Extraction of pion and kaon PDFs from Drell-Yan and charmonium production data in the statistical model

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.

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

PACSPIN_2024_Peng.pdf

10:15 AM → 10:30 AM Coffee break

10:30 AM → 12:15 PM Plenary: Nov 11, morning 2

Convener: Shinya Sawada

10:30 AM Compass SIDIS

Speaker: Andrea Bressan

4_SIDIS_Bressan.pptx

11:05 AM GPD Measurement at the COMPASS Experiment

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.

Speaker: Po-Ju Lin (National Central University)

12PacificSpin_Hefei_COMPASS_pjlin.pdf

11:40 AM Proton spin decomposition from a light-front Hamiltonian approach

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.

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

6_for_prof_zhao_20241111.pdf

12:15 PM → 2:00 PM Lunch break

2:00 PM → 4:10 PM Plenary: Nov 11, afternoon 1

Convener: Yubing Dong (Institute of High Energy Physics,CAS)

2:00 PM Constraining the collision terms in spin kinetic theory

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.

Speaker: Jian-hua Gao

Constraints-Jian-Hua Gao.pptx

2:35 PM Transverse spin asymmetry as a probe of new physics beyond the SM

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.

Speaker: Yan Bin (IHEP)

spin_asy_BY.pdf

3:10 PM Global analysis of GPDs with moment-space parameterization

Speaker: Yuxun Guo

PacificSpin2024_Yuxun_Guo.pdf

3:40 PM Polarized gluon distribution

Speaker: Yiyu Zhou

4_Yiyu-Zhou.pdf

4:10 PM → 4:25 PM Coffee break

4:25 PM → 6:20 PM Parallel session A

Convener: Andrea Bressan

4:25 PM Progress on Constraining the Strange Quark Contribution to the Proton Axial Form Factor

We report on a global fit of neutral-current elastic (NCE) neutrino-scattering data and parity-violating electron-scattering (PVES) data with the goal of determining the strange quark contribution to the vector and axial form factors of the proton. Knowledge of the strangeness contribution to the axial form factor, $G_A^s(Q^2)$, at low $Q^2$ will reveal the strange quark contribution to the nucleon spin, as $G_A^s(Q^2=0)=\Delta s$. Previous fits [1,2] of this form included data from a variety of PVES experiments (PVA4, HAPPEx, G0, SAMPLE) and the NCE neutrino and anti-neutrino data from BNL E734. These fits did not constrain $G_A^s(Q^2)$ at low $Q^2$ very well because there was no NCE data for $Q^2<0.45$ GeV$^2$. Our new fit includes for the first time MiniBooNE NCE data from both neutrino and anti-neutrino scattering; this experiment used a hydrocarbon target and so a model of the neutrino interaction with the carbon nucleus was required. Three different nuclear models have been employed; a relativistic Fermi gas (RFG) model, the SuperScaling Approximation (SuSA) model, and a spectral function (SF) model [3]. We find a tremendous improvement in the constraint of $G_A^s(Q^2)$ at low $Q^2$ compared to previous work, although more data is needed from NCE measurements that focus on exclusive single-proton final states, for example from MicroBooNE [4]. This work has been published in Physical Review D [5].

[1] S.F. Pate, D. McKee, V. Papavassiliou, Phys. Rev. C78, 015207 (2008)
[2] S.F. Pate, D. Trujillo, EPJ Web of Conferences 66, 06018 (2014)
[3] C. Giusti and M.V. Ivanov, J. Phys. G: Nucl. Part. Phys. 47 024001 (2020)
[4] L. Ren, NuFact 2021, PoS, 402, 205 (2022), 10.22323/1.402.0205
[5] S.F. Pate et al., Phys. Rev. D 109, 093001, 2024

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

SFP_PacificSpin2024_GAs.pdf

4:45 PM Longitudinal double spin asymmetry of $\Lambda$, $\overline{\Lambda}$, $K_S^0$ and inclusive jets with high-$z$ $\pi^{\pm}$ tagging in polarized proton-proton collisions at $\sqrt{s}=200$ $\rm{GeV}$ at STAR

Unraveling the proton spin composition, comprising intrinsic spins and angular momenta of quarks and gluons, stands as one of the most fundamental and challenging questions in QCD. Much progress has been made since the first surprising result by the EMC experiment in the late 1980s. However, the helicity distributions of strange quarks and anti-quarks inside the proton are still not well constrained by the experimental data.
Measurement of the longitudinal double spin asymmetry, $A_{LL}$, of $\Lambda$, $\overline{\Lambda}$ and $K_S^0$ in the longitudinally polarized proton-proton collisions can shed light on the strange quark and anti-quark helicity distributions. In addition, the $A_{LL}$ of the inclusive jets tagged with a $\pi^+/\pi^-$ carrying high jet momentum fraction, $z$, in proton-proton collisions can provide further constraints on the gluon helicity distribution in the proton.

In this talk, we will present the preliminary results of the $A_{LL}$ for $\Lambda$, $\overline{\Lambda}$ and $K_S^0$, and the inclusive jets tagged with a high-$z$ $\pi^{\pm}$ from the longitudinally polarized proton-proton collisions at $\sqrt{s}=200$ $\rm{GeV}$ collected by the STAR experiment with an integrated luminosity of about 52 $\rm{pb^{-1}}$.

Speaker: Yi Yu (Shandong University)

PacificSpin_slides_YiYu.pdf

5:05 PM Transverse momentum dependent helicity distributions

In this talk, I will present the first extraction of TMD helicity distributions, by analyzing double spin asymmetry data from SIDIS.

Speaker: Ke Yang (Peking University)

Ke-Yang-2024-11-Hefei-v3.pdf

5:25 PM Global analysis of Sivers and Collins asymmetries within TMD factorization

we present a global analysis of Sivers function, transversity distribution functions and Collins fragmentation func-
tions within TMD factorization. This analysis encompasses the latest data sets from semi-inclusive deep inelastic scattering, Drell-
Yan, and W±/Z-boson production as recently reported by the COMPASS and STAR Collaborations. Upon integrating this new data
into our fitting, the accuracy of the d and ¯d quark extraction for both transversity and Sivers distribution is notably improved.

Speaker: chunhua zeng (Institute of Modern Physics)

曾春华_合肥报告.pdf

5:45 PM Azimuthal transverse single-spin asymmetries of inclusive jets and hadrons within jets from polarized ${pp}$ collisions at RHIC-STAR

The study of the origins of transverse single-spin asymmetries has stimulated significant progress in the development of twist-3 formalism and transverse-momentum-dependent parton distribution functions (TMDs). Measurements of the azimuthal distribution of inclusive jets and identified hadrons within jets produced in transversely polarized hadronic interactions provide key insights into TMD physics. In particular, measurements of the Collins effect, which involves the interplay between the quark transversity and Collins fragmentation function, provide access to the final-state phenomena of TMD physics. The STAR collaboration has previously reported measurements of Collins asymmetries from jet + $\pi^{\pm}$ production in transversely polarized proton-proton (${pp}$) collisions at a center-of-mass energy of $\sqrt{s} = 500$ GeV, based on data collected in 2011 with an integrated luminosity of 23 $\mathrm{pb}^{-1}$. Furthermore, comprehensive studies of azimuthal transverse single-spin asymmetries for hadrons within jets from ${pp}$ collisions at $\sqrt{s} = 200$ GeV were conducted using data from 2012 and 2015. In 2017, STAR accumulated a significantly larger ${pp}$ dataset, with an integrated luminosity of 320 $\mathrm{pb}^{-1}$ at $\sqrt{s} = 510$ GeV, which is expected to substantially improve the precision of transverse single-spin asymmetry measurements, especially in the high jet transverse momentum region. This presentation reports preliminary results on azimuthal transverse single-spin asymmetries for charged pions within jets from transversely polarized ${pp}$ collisions at $\sqrt{s} = 510$ GeV. The comparison of Collins asymmetries between ${pp}$ collisions at 200 GeV and 510 GeV can provide crucial insights into the energy evolution of the Collins function. Additionally, comparing experimental results from ${pp}$ collisions with theoretical predictions derived from global fits to semi-inclusive deep inelastic scattering and $e^+e^-$ annihilation data will allow tests of the universality of Collins asymmetries.

Speaker: Yixin Zhang (Shandong University)

PacificSpin2024_YixinZhang.pdf

6:05 PM New Way of Generating Odderon Contribution to Single Spin Asymmetry

Nuclear dependence of Single Transverse Spin Asymmetry (STSA) in pp and pA collisions is still a standing mystery. Recent results by PHENIX (A^(−1/3)) [1]
and STAR (A^0) [2] collaborations posses strikingly different nuclear scaling which suggest that the dominant underlying mechanism for STSA may vary with
the kinematics of the collision. In the forward regime, where the gluon saturation effects become important, and where the collisions are described in the
so-called hybrid formalism [3], two contributions to STSA in pp and pA collisions have been found [4,5]. In [5], the phase required for STSA comes from the
imaginary part of twist-3 fragmentation function (FF) with the polarized projectile described with Transversity parton distribution function and the unpolarized
target with real part of Dipole distribution, Pomeron. We have found a new contribution to STSA [Benić, Vivoda in preparation] which comes from the
combination of the real part of genuine twist-3 FF and the imaginary part of dipole distribution, Odderon. The Odderon mechanism to STSA is known to generate
significant nuclear dependance [6] and we expect that this approach could shine a new light at RHIC data [1,2]. Also, this contribution will give us some insight
into the real part of the twist-3 FF which has not yet been constrained by global fits [7]. In this talk I will first provide a formula for polarized cross section and
then discuss our numerical results for STSA [Benić, Vivoda in preparation].

References:
[1] C. Aidala et. al. (PHENIX Collaboration), Phys. Rev. Lett. 123, 122001 (2019).
[2] J. Adam et. al. (STAR Collaboration), Phys. Rev. D 103, 072005 (2021).
[3] A. Schafer and J. Zhou, Phys. Rev. D 90, 034016 (2014), 1404.5809.
[4] Y. Hatta, B.-W. Xiao, S. Yoshida and F. Yuan, Phys. Rev. D 94, 054013 (2016).
[5] Y. Hatta, B.-W. Xiao, S. Yoshida and F. Yuan, Phys. Rev. D 95, 014008 (2017).
[6] Y. V. Kovchegov and M. D. Sievert, Phys. Rev. D 86, 034028 (2012), [Erratum: Phys.Rev.D 86, 079906 (2012)].
[7] L. Gamberg et al. (Jefferson Lab Angular Momentum (JAM) Collaboration), Phys. Rev. D 106, 034014 (2022).

Speaker: Eric Andreas Vivoda (Department of Physics, Faculty of Science, University of Zagreb)

PacificSpin2024EAVivoda.pdf

4:25 PM → 6:10 PM Parallel session B

Convener: Xu-Guang Huang

4:25 PM Effect of Coriolis force on the shear viscosity of quark matter: A nonrelativistic description

Shear viscosity becomes anisotropic in a rotating medium. It is discovered here that for rotating thermalized quantum systems such as those created in relativistic heavy-ion collisions, the coefficient of shear viscosity breaks up into five independent components. Similar phenomena were also discovered for quark-gluon plasma in the presence of the magnetic field. Like the Lorentz force at a finite magnetic field, the Coriolis force also creates anisotropic viscosity at nonzero rotation. As a first approach, for simplicity, the calculations are done in the nonrelativistic prescription, with a future proposal to extend it toward a relativistic description. Introducing the Coriolis force term in relaxation time approximated Boltzmann transport equation, we have found different effective relaxation times along the parallel, perpendicular, and Hall directions in terms of actual relaxation time and rotating time period. Comparing the present formalism with the finite magnetic field picture, we have shown the equivalence of roles between the rotating and cyclotron time periods, where the rotating time period is inverse of twice the angular velocity.

DOI: 10.1103/PhysRevC.109.034913

Speaker: Cho Win Aung (Indian Institute of Technology Bhilai)

PacificSpin_2024_ppt (1).pdf

4:45 PM Measurements of Global and Local Polarization of Hyperons in Heavy Ion Collisions from STAR

The observation of hyperon polarization has revealed the existence of large vorticities in the medium created by heavy-ion collisions. Global polarization indicates vorticities perpendicular to the reaction plane due to the system's orbital angular momentum.
Using the high-statistics data collected by the STAR experiment during the RHIC BES-II program with upgraded detector systems, we present the global polarization measurements for $\Lambda$, $\bar{\Lambda}$ and $\Xi^{\pm}$ hyperons for Au+Au collisions at BES-II energies ($\sqrt{s_{\mathrm{NN}}} = 7.7 - 27$ GeV). These measurements allow us to study possible magnetic field driven effects through the polarization difference between $\Lambda$ and $\bar{\Lambda}$ hyperon.
Anisotropic transverse expansion of the medium generates vorticities along the beam direction, which consequently result in polarization for hyperons, referred to as local polarization. We present the measurements of $\Lambda$, $\bar{\Lambda}$ hyperon local polarization in isobar collisions at $\sqrt{s_{\mathrm{NN}}} = 200$ GeV and Au+Au collisions at BES-II energies. These results provide new insights into polarization mechanism and vorticity fields in heavy-ion collisions as well as additional constraints on properties and dynamics of the matter created in the collisions.

Speaker: Dr Xingrui Gou (Shandong University)

PacificSpin2024_Xingrui_v2.pdf

5:05 PM Bell-Clauser-Horne Inequalities and Generalized Quantum Measurements in Spin-Correlated Hyperon-Antihyperon Decays: A Framework for Probing Quantum Nonlocality in Spin Physics

Quantum nonlocality, a fundamental feature of quantum mechanics, is frequently associated with the experimental violation of Bell-Clauser-Horne (Bell-CH) inequalities. We present a set of novel methods for the rearrangement and linear inequalities to derive a broad class of Bell-CH inequalities, which can be violated by particular quantum-entangled states. The rapid advancements in Quantum Information Science (QIS) have opened new avenues for probing fundamental aspects of physics. Central to distinguishing quantum information from classical information, quantum nonlocality has been extensively investigated through the violation of Bell-CH inequalities in particle decay processes. Nonetheless, a comprehensive framework grounded in quantum information theory for particle interactions remains elusive. To bridge this gap, we propose a generalized quantum measurement framework for spin-1/2 hyperon decay processes, aligning this approach with established theoretical models and applying it to the joint decay of correlated $\Lambda\bar{\Lambda}$ pairs. Utilizing quantum simulations, we demonstrate the violation of Bell-CH inequalities in hyperon decays. This generalized measurement framework is versatile and can be extended to a range of high-energy processes, including the decays of vector mesons, $J/\psi$ and $\psi(2S) \to \Lambda\bar{\Lambda}$, within the Beijing Spectrometer III (BESIII) experiment at the Beijing Electron Positron Collider (BEPC).

Speaker: Dr Yangguang Yang (Institute of Modern Physics, Chinese Academy of Sciences)

PacificSpin2024_YGY.pdf

5:25 PM Late-time asymptotic solutions, attractor, and focusing behavior of spin hydrodynamics

We have investigated the late-time asymptotic solutions, attractor, and focusing behavior of minimal causal spin hydrodynamics in Bjorken expansion. Using the method of dominant balance, we derive the late-time asymptotic solutions of the evolution equation for spin density and identify the specific conditions necessary for the spin density to exhibit a power-law decay. We then analyze both the late-time and early-time attractors for the decay rate of spin density. Additionally, we report the focusing behavior in spin hydrodynamics, which has not been found in conventional relativistic hydrodynamics in Bjorken expansion. Our findings suggest that spin density can be treated as a conventional hydrodynamic variable at late times under certain conditions.

Speaker: Dong-Lin Wang (USTC)

4_DongLinWang_241111.pdf

DongLinWang_v2_241111.pdf

5:40 PM Spin polarization of Lambda hyperons along beam direction in p+Pb collisions at s=8.16 TeV using hydrodynamic approaches

We have implemented the 3+1 dimensional CLVisc hydrodynamics model with TRENTO-3D initial conditions to investigate the spin polarization of Lambda hyperons along the beam direction in p+Pb collisions at
sNN= 8.16 TeV. Following our previous theoretical framework based on quantum kinetic theory, we consider three different scenarios: Lambda equilibrium, s quark equilibrium, and iso-thermal equilibrium scenarios. We have computed the second Fourier sine coefficients of spin polarization along the beam direction, Additionally, we have also computed the spin polarization along the beam direction. We find that the spin polarization induced by thermal vorticity always provides an opposite contribution compared to the shear-induced polarization in p+Pb collisions. The total spin polarization computed by the current hydrodynamic model disagrees with the data measured by LHC-CMS experiments. Our findings imply that other non-flow effects may play a crucial role in p+Pb collisions.

Speaker: Cong Yi (USTC)

CongYi_spin_polarization_1111.pdf

5:55 PM Spin polarization and spin alignment from quantum kinetic theory with self-energy corrections

We derive the quantum kinetic theory for massive fermions with collision terms and self-energy corrections based on quantum field theory. We adopt an effective power-counting scheme with \hbar expansion to obtain the leading-order perturbative solutions of the vector and axial Wigner functions and the corresponding kinetic equations. We observe that both the on-shell relation and the structure of Wigner functions, along with the kinetic equations, are modified due to the presence of self-energies and their spacetime gradients. We further apply our formalism to investigate the spin polarization phenomena in relativistic heavy ion collisions and derive the modification to the spin polarization spectrum of massive quarks. We find that the gradient of vector self-energy plays a similar role to the background electromagnetic fields, which induces a more dominant contribution than the collisional effects by a naive power counting in the gradient expansion and weak coupling. Our findings could further modify the spin polarization of strange quarks and the spin alignment of
\phi mesons beyond local thermal equilibrium.

Speaker: Shuo Fang (USTC)

6_CollisionCorrections_ShuoFang241111.pdf

7:00 PM → 9:00 PM Dinner

Tuesday, November 12

8:30 AM → 10:15 AM Plenary: Nov 12, morning 1

Convener: Luciano Libero Pappalardo (University of Ferrara, Italy)

8:30 AM New insight into the structure of baryon excited states

Speaker: Anthony W. Thomas

AW Thomas Pacific-Spin 2024 Heifei China.pdf

9:05 AM J-PARC and its hadronic physics program

The Japan Proton Accelerator Research Complex, J-PARC, is a multi-purpose accelerator facility utilizing its high-intensity proton beams. The accelerators are cascaded from the 400-MeV Linac, the 3-GeV Rapid Cycling Synchrotron, and the 30-GeV Main Ring. The
Hadron Experimental Facility (HEF) uses slowly extracted 30-GeV proton beams from MR, where particle and hadronic physics experiments are being conducted. In this talk, the overview of the facility will be introduced and the current and future programs mainly at HEF will be discussed.

Speaker: Shinya Sawada

2 Sawada-J-PARCandHadronicPhysics-20241112.ppt

9:40 AM The SPD project at NICA.

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.

Speaker: Alexey Guskov (Joint Institute for Nuclear Research, Dubna)

SPD_Pacific_spin.pdf

10:15 AM → 10:30 AM Coffee break

10:30 AM → 12:15 PM Plenary: Nov 12, morning 2

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

10:30 AM Experimental study of fragmentation functions at BESIII and STCF

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.

Speaker: Yateng ZHANG (ZZU)

Experimental study of fragmentation functions at BESIII.pdf

11:05 AM Fragmentation functions from Belle I & Belle II

Speaker: Simon Schneider

PacificSpinBelleFFs.pdf

11:40 AM Electron-Ion Collider in China (EicC)

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.

Speaker: Yuxiang Zhao (Institute of Modern Physics)

Yuxiang_EicC_PacificSpin.pdf

12:15 PM → 2:00 PM Lunch break

2:00 PM → 3:45 PM Plenary: Nov 12, afternoon 1

Convener: Julie Roche (Ohio University)

2:00 PM Generalized parton distributions of spin-3/2 particles

Speaker: Yubing Dong

1_DYBPacificSpin-2024(11-12).pdf

2:35 PM QCD sum rules for hadron spin decomposition

Speaker: Hyungjoo Kim (Hiroshima University)

PacificSpin2024_HJK.pdf

3:10 PM Lambda polarization in deep inelastic scattering

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.

Speaker: Tianbo Liu (Shandong University)

20241112 Lambda polarization in deep inelastic scattering.pdf

3:45 PM → 4:00 PM Coffee break

4:00 PM → 5:45 PM Plenary: Nov 12, afternoon 2

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

4:00 PM Parton distribnution functions in tensor-polarized spin-1 hadrons

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.

Speaker: Qintao SONG (Zhengzhou University)

spin-1 structure.pdf

4:35 PM Current status of the theoretical study on the single spin asymmetry and prospects at the future experiment

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.

Speaker: Shinsuke Yoshida (South China Normal University)

Pacspin2024_yoshida.pptx

5:10 PM PDF on lattice

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

PDF on Lattice QCD.pptx

5:45 PM → 6:15 PM Closing remarks (Qun Wang)

7:00 PM → 9:00 PM Dinner

Wednesday, November 13

9:00 AM → 11:30 AM Free discussion

11:30 AM → 11:50 AM Adjourn