Welcome remark from Academician Yuan Liang, President of Anhui University of Science and Technology
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...
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...
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....
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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,...
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...
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...
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...
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...
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...
In this talk, I will present the first extraction of TMD helicity distributions, by analyzing double spin asymmetry data from SIDIS.
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,...
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...
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...
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...
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...
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...
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 $10^{32}$...
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...
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...
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...
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...
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)...