11th Asian Triangle Heavy-Ion Conference

5 Nov 2026, 08:00 → 9 Nov 2026, 17:00 Asia/Shanghai

Shanghai Science Hall (Shanghai)

Overview

 

The 11th Asian Triangle Heavy-Ion Conference (ATHIC 2026) will be hosted by Fudan University in Shanghai, China. The conference will take place at the Shanghai Science Hall, Shanghai, from Thursday, November 5th to Monday, November 9th, 2026. Please note that November 5th is reserved for registration. The conference is supported by the Shanghai Nuclear Society, the Shanghai Physical Society, among others.

ATHIC 2026 continues the tradition of previous conferences, which began in Seoul in 2006, with the most recent one held in Odisha in 2025. Many physicists from Asian countries have been actively engaged in both experimental and theoretical research on heavy-ion collisions. ATHIC provides a platform for these researchers to gather and discuss exciting developments in the field. We look forward to fostering fruitful discussions among participants and generating new ideas to advance our understanding of hot and dense QCD matter.

ATHIC 2026 will focus on a wide range of topics, including but not limited to:

• Initial state and thermalization
• Jets and medium response
• Heavy quarks and quarkonia
• Electromagnetic probes
• Collective dynamics
• Correlations and fluctuations
• QCD phase diagram and extreme conditions
• QGP in small systems
• Strong fields, spin and vorticity
• Hadronic interactions and exotic states
• New theoretical developments
• Experimental techniques and future programs

The conference will feature plenary, parallel, and poster sessions. Students are especially encouraged to submit their contributions. 

ATHIC2026_Conference_English_Transportation_and_Accommodation_Guide_20261025.pdf

ATHIC2026Handbook_20261031.pdf

ATHIC2026posterschedule-20261031.pdf

ATHIC2026会议电子中文版交通住宿指南-20261025.pdf

DigitalPay_Guide.pdf

Thursday 5 November

Onsite registration

Friday 6 November

Welcome address

1 Experimental Overview of QCD Phase Diagram under Extreme Conditions

Speaker: Ashish Pandav (Kent State University)

2 Toward Precision Fluctuation Measurements in Heavy-Ion Collisions

Speaker: Toshihiro Nonaka (CCNU)

3 Searching for the QCD Critical Point in Hydro-Evolution

Speaker: Noriyuki Sogabe (Osaka University)

Group Photo & Coffee Break

4 Experimental Overview of Jet Physics in Heavy-Ion Collisions

Speaker: Maowu Nie (Shandong University)

5 Jet quenching and jet-induced medium response

Speaker: Zhong Yang (Vanderbilt University, USA)

Lunch (Buffet)

6 Experimental Probes of Thermalization and Hadronization in Heavy-Ion Collisions

Speaker: Bong-Hwi Lim (Univ. of Tokyo)

7 Understanding quarkonia production in pPb and OO with CMS

Speaker: Soohwan Lee (Korea University)

8 Heavy quark systems in QGP: recent lattice results

Speaker: Saumen Datta (TIFR, Mumbai)

9 Realizing the discovery potential of heavy quarkonia in HICs

Speaker: Alexander Rothkopf (Korea University)

Coffee Break

10 Hadronic Interactions and Exotic States

Speaker: Nilmani Mathur (TIFR)

11 Recent developments in EFT in matter

Speaker: Rishi Sharma (TIFR)

12 Harmonic Flow in a Strongly Interacting Fluid

Elliptic flow constitutes the hallmark observable of collective dynamics in heavy-ion collisions, revealing hydrodynamic properties of dense nuclear matter. Strongly interacting Fermi gases provide a clean, controllable strongly correlated quantum fluid to study universal phenomena, bridging ultracold atom experiments and nuclear physics. This talk will focus on higher-order harmonic flow extending beyond elliptic flow. We examine how initial spatial eccentricity generates azimuthal momentum anisotropies at multiple harmonic orders in expanding Fermi gases, and draw parallels with anisotropic flow measurements from heavy-ion experiments. The observed scaling highlights universal features of shear viscosity, thermalization, and nonlinear response in strongly coupled systems.

Speaker: Haibin Wu (East China Normal University)

Harmonic Flow Expansion.pdf

13 Constraining medium properties from jets and substructures

Speaker: Weiyao Ke

Saturday 7 November

14 The development of Hyperon-Nucleon Spectrometer at HIAF and future EicC

Speaker: Nu Xu

15 Imaging nuclear structure in high-energy nuclear collisions: from heavy to light ions

Speaker: Chunjian Zhang (Fudan University)

16 Recent Results on φ-Meson Production in pA Reactions at J-PARC E16

Speaker: Satomi Nakasuga (Kyoto U.)

Coffee Break

17 Machine learning for Heavy-ion Collisions

Speaker: Longgang Pang (CCNU)

18 Exploring High-Energy Nuclear Collisions with Hydro-based Event Generators

Speaker: Shin-ei Fujii (Sophia University/Zhejiang University)

19 Theoretical progress on vector meson spin alignment in heavy-ion collisions

Speaker: Xin-Li Sheng (Fudan University/Goethe University Frankfurt)

Lunch (Buffet)

20 Probing Vorticity and Strong Fields through Hadron Spin in Heavy-Ion Collisions

Speaker: Prottay Das (CERN)

21 Probing the Nucleon D-term with Quarkonium–Nucleon Femtoscopy

Speaker: Ren Ejima (Tokyo University)

Poster Session

Banquet

Sunday 8 November

Parallel 1

22 The non-linear response coefficient $\chi_{4,22}$ in Au+Au and U+U collisions

Relativistic heavy-ion collisions offer a unique opportunity to probe the deformation of colliding nuclei. The quadrupole deformation parameter $\beta_{2}$ has been extensively studied through the flow coefficient $v_2$ in such collisions, as well as through low-energy measurements of the electric quadrupole transition probabilities, $\rm B(E_{2})$. In contrast, the hexadecapole deformation parameter ($\beta_{4}$) has often been neglected in modeling heavy-ion collisions, primarily due to large experimental and theoretical uncertainties. The non-linear response coefficient $\chi_{4,22}$ quantifies the strength of the coupling between the second-order and the fourth-order flow harmonic. This coefficient is sensitive to higher-order nuclear deformations such as $\beta_{4}$, which modulate the initial geometry beyond simple ellipticity. In this talk, we present measurements of $\chi_{4,22}$ in Au+Au and U+U collisions at 200 GeV and 193 GeV, respectively. A deviation of the $\chi_{4,22}$ ratio between U+U and Au+Au collisions from unity was observed in central collisions. The results were compared with calculations from the iEBE-VISHNU hydrodynamic and AMPT models, where the $^{238}$U $\beta_4$ predicted by nuclear structure theory calculations is incorporated. The comparison indicates that the observed deviation favors a sizeable hexadecapole deformation of the $^{238}$U nucleus.

Speaker: Jie Zhao (Fudan)

23 Rotation catalyzed chiral magnetovortical instability

Chiral matter exhibits a variety of intriguing anomalous transport phenomena that originate from the chiral anomaly. Prominent examples of such phenomena include the chiral magnetic effect and the chiral vortical effect. In the hydrodynamic regime, we demonstrate that in a chiral plasma subject to an external magnetic field, the chiral vortical effect can induce a new type of magnetohydrodynamic instability called the chiral magnetovortical instability [1]. Furthermore, a background rotation will significantly catalyze the chiral magnetovortical instability and make it occur more easily [2]. In particular, this gives rise to a rapid growth of low-frequency wave modes. These results reveal the helicity transport between chiral fermions and macroscopic helicities. Our findings suggest a variety of possible implications for chiral matters, like the quark-gluon plasma in heavy-ion collisions.

[1]S.Wang and X.-G.Huang, Phys.Rev. D109, L121302(2024).
[2]S.Wang and X.-G.Huang, Phys.Rev. D113, 116033 (2026).

Speaker: Dr Shuai Wang (Fudan University)

24 Universality and Attractors of Heavy Quark Transport in Lead-Lead (Pb-Pb) Collisions.

Heavy quarks are produced in hard scatterings at the very beginning of a heavy-ion collision. As a result, they experience all subsequent stages of the collision, and their dynamics are particularly sensitive to the properties of the quark–gluon plasma (QGP) phase. Recent studies have demonstrated that a fluid-dynamical description of heavy-quark transport in the QGP, combined with a realistic hadronization and freeze-out procedure, can reproduce experimental particle spectra with remarkable precision. While this success is widely acknowledged, its underlying reasons are not yet fully understood.

In this talk, I discuss the dynamics of heavy quarks in the QGP, focusing on their thermalization — or hydrodynamization — within the finite lifetime of the medium. I present signatures of thermalization, universal behavior, and (hydrodynamic) attractors that govern heavy-quark evolution even far from equilibrium.

Speaker: Ruwen Schulz (Institute of Physics, Heidelberg, Germany)

25 Understanding Baryon Stopping and Baryon Diffusion from Baryon-AntiBaryon Elliptic Flow Splitting

The medium produced at RHIC Beam Energy Scan (BES) energies is baryon-rich. This enhanced baryon stopping not only leads to a splitting in the yields of baryons and anti-baryons, but has also been observed experimentally to produce a splitting in their flow coefficients. Hydrodynamic models have struggled to reproduce this baryon-antibaryon flow splitting with the correct magnitude and sign, largely because of inadequate modeling of the initial net-baryon profile. In this work, we propose a novel baryon deposition ansatz that goes beyond the commonly employed factorization approach, in which the transverse and longitudinal components of the deposition are treated independently. Instead, our model allows the rapidity extent of the baryon profile to depend explicitly on the transverse position. Specifically, we introduce a density-dependent baryon stopping prescription in which the rapidity loss of a participant nucleon depends on the local density of participants from the opposing nucleus. When this initial condition is combined with a tilted energy deposition and incorporated into a hydrodynamic framework with finite baryon density and baryon diffusion, it successfully captures the splitting of both $v_1$ and $v_2$ between baryons and anti-baryons, a feature that theoretical models have long struggled to explain. This combined initial condition and hydrodynamic framework therefore provides a robust baseline for predictions relevant to the search for the QCD critical point and for electromagnetic field signatures and future measurements.

Speaker: Ms Priya (Department of Physical Sciences, Indian Institute of Science Education and Research Berhampur, Laudigam--760003, Dist.--Ganjam, Odisha, India)

ATHIC2026_abstract_final.pdf

26 Longitudinal Decorrelations in Proton-Proton Collisions from AMPT with Sub-Nucleon Spatial Fluctuations

Recent experimental observations of collective-like phenomena in small collision systems, such as pp collisions, have challenged traditional paradigms and highlighted the critical role of initial-state geometry and its fluctuations. In particular, longitudinal decorrelations serve as a powerful probe of the three-dimensional initial-state structure and longitudinal dynamics of the collision system. In this work, we investigate longitudinal decorrelations in pp collisions at 13 TeV using a modified version of the AMPT model in which the conventional nucleon profile is replaced by a sub-nucleonic structure consisting of localized constituent-quark hotspots. This additional spatial granularity generates substantially stronger event-by-event fluctuations in the initial geometry. We find that incorporating three constituent-quark hotspots per nucleon significantly enhances the magnitude of longitudinal decorrelations compared with conventional point-like nucleon initial conditions. By studying the evolution from the fluctuating initial state to the final-state partonic dynamics within AMPT, we further investigate how initial-state sub-nucleon structure influences longitudinal correlations and the emergence of collectivity in small systems. These results demonstrate the importance of sub-nucleon degrees of freedom for describing longitudinal dynamics in pp collisions and provide new constraints on models of the initial state in small collision systems.

Speaker: Liang Zheng

27 Deciphering the universal scaling of particle transverse momentum spectra in heavy-ion collisions

We systematically investigate the scaling properties of the transverse momentum spectra for pions, kaons, and protons in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV, as well as in U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV, across different centrality classes, using experimental data from the collaborations at the Relativistic Heavy Ion Collider (RHIC). Universal scaling emerges when the particle transverse momentum spectra are scaled by global physical quantities, i.e., the average total particle multiplicity and mean transverse momentum, confirming recent scaling findings from the data at the Large Hadron Collider (LHC) by the ExTrEMe collaboration. The scaling behavior breaks down in the high $p_{\rm T}$ region and in peripheral collisions. We provide a natural explanation for these observations in the framework of a blast-wave-type model built upon the Cooper-Frye formula. Furthermore, we demonstrate the equivalence between the scaling found by the ExTrEMe collaboration and the Hwa-Yang scaling which was proposed two decades ago.

Speaker: Xiyao Guo (Shaanxi Normal University)

Parallel 2

28 Spin Alignment and Phase Transition of QGP in the Presence of Magnetic and Vorticity Fields

We will study the Spin Alignment and Phase Structure of Thermal QGP under Rotation with high energy heavy-ion collisions.And then,we will investigate the Anomalous Magnetic Moment and Phase Transition of the Magnetized QCD Background; The Rotation Effect on the Deconfinement Phase Transition are investigated with Holographic QCD method. And finally, we make Summary and Conclusions.

Speaker: Prof. Sheng-Qin Feng (Three Gorges University)

29 Charged pseudoscalar mesons in a strong magnetic field under the Weinberg model

Recent lattice QCD simulations have further validated their earlier unusual findings: The lowest energies of charged pseudoscalar mesons $\pi^\pm$ and $K^\pm$ decrease at stronger magnetic field, though quasiparticle approximation assumes an increasing feature. We address this long-standing puzzle by employing the chiral effective Weinberg model, in which pseudoscalar and vector mesons exhibit intrinsic mutual couplings. Under this framework, charged pseudoscalar mesons deviate from pure quasiparticle behavior due to their interactions with neutral pseudoscalar and charged vector mesons. By incorporating the modifications induced by neutral pseudoscalar-charged vector loops, we demonstrate that the lowest energies of $\pi^\pm$ and $K^\pm$ indeed decrease at stronger magnetic field in both the lowest- and full-Landau-level calculations. However, instabilities emerge under a fixed mesonic coupling constant, and appear unavoidable when attempting to reproduce the observed peak structures. In contrast to the quark-antiquark meson description in models such as the NJL model, our results support the conjecture that a charged pseudoscalar meson could effectively form a molecular bound state of a neutral pseudoscalar meson and a charged vector meson in the strong magnetic field regime.

Speaker: 高清 曹

30 Thermodynamics and Polyakov-loop Potential of Accelerated Gluonic Matter

In this talk, I will report our recent study of the thermodynamics of accelerated pure gluonic matter. We investigate the one-loop Polyakov-loop effective potential in uniformly accelerated systems, where acceleration serves as an external parameter for the confinement--deconfinement transition. We compare thermodynamic quantities obtained in the Rindler frame with those in the conformally related optical frame, and clarify the relation between the free energy and the pressure in accelerated systems. Based on this framework, we derive the one-loop Polyakov-loop effective potential and find that increasing acceleration favors the deconfined phase, indicating that acceleration enhances deconfinement in pure Yang--Mills theory.

Speaker: Hao-Lei Chen (Shanghai University)

31 Probing (Hyper)Nuclei Wave Functions and Production Mechanisms in √sNN = 200 GeV Isobar Collisions at RHIC

The production of light nuclei and hypernuclei in relativistic heavy-ion collisions provides a unique opportunity to investigate the formation mechanism of loosely bound states and the structure of hypernuclei. In particular, coalescence models predict a strong suppression of hypertriton (${}^{3}_{\Lambda}\mathrm{H}$) production relative to ${}^{3}\mathrm{He}$ in small collision systems because of the large spatial extent of the hypertriton wave function.

In this talk, we will present measurements of light nuclei ($t$, ${}^{3}\mathrm{He}$, and ${}^{3}\overline{\mathrm{He}}$) and hypernuclei (${}^{3}_{\Lambda}\mathrm{H}$ and ${}^{3}_{\bar{\Lambda}}\overline{\mathrm{H}}$) production at mid-rapidity in Ru+Ru and Zr+Zr collisions at $\sqrt{s_{\rm NN}}=200$ GeV with the STAR experiment. The multiplicity dependence of the yield ratios $N_tN_p/N_d^2$ and $S_{3} =(N_{{}^{3}_{\Lambda}\rm{H}}/N_{{}^{3}_{}\rm{He}})/(N_{\Lambda}/N_{p})$ will be discussed and compared with thermal and coalescence model calculations. The measurements show significant deviations from thermal-model expectations, while coalescence calculations incorporating realistic non-Gaussian wave functions for $d$ and ${}^{3}_{\Lambda}\mathrm{H}$ provide an improved description of the data. The results suggest that the hypertriton wave function has a larger short-distance $d$--$\Lambda$ probability than implied by a Gaussian ansatz, demonstrating the potential of heavy-ion production measurements as a probe of hypernuclear wave functions and the underlying hyperon--nucleon interaction.

Speaker: Hui Liu (Huzhou Normal University)

32 Analytical structure of the Polyakov-loop extended Quark-Meson model

Lee-Yang edge singularities (LYEs) are singularities that limit the analyticity of the thermodynamic potential in the complex chemical potential plane and provide important information on the phase structure. In this work, we extend the functional renormalization group approach for the PQM model to the complex chemical potential plane and investigate its analytic structure. We identify the chiral and Roberge-Weiss LYEs. The chiral LYEs move toward the real chemical potential axis as the temperature decreases, eventually reaching the real axis at the critical endpoint. The scaling behavior of LYEs is investigated, and one critical exponent is determined. We further analyze the LYE modes and their composition, particularly the mixing between the chiral and Polyakov-loop degrees of freedom. This study also provides useful insights into the convergence properties of thermodynamic observables and the calculation of the net-baryon number probability distribution.

Speaker: RUI WEN (Yantai University)

33 Production of light nuclei in Au+Au collisions with the STAR BES-II program

Studies of light nucleus production, including deuterons, and helium nuclei, in heavy-ion collisions are essential for understanding the dynamics of nuclear matter under extreme conditions and provide valuable insights into the underlying equation of state. Compound yield ratios, such as $\rm N_t \times N_p/N_d^2$ and $\rm N_{^4He} \times N_p / (N_{^3He} \times N_d)$, have been proposed as probes of local baryon-density fluctuations and possible critical behavior in quantum chromodynamics (QCD). In addition, the yields and ratios of light nuclei can help constrain thermal-statistical and coalescence descriptions. The larger STAR BES-II datasets extended energy coverage toward higher net-baryon density, and improved detector capabilities enable more precise and comprehensive measurements than BES-I.

In this talk, we will present the energy dependence of the coalescence parameters $(B_\mathrm{A})$ and particle yield ratios involving p, d, $\rm ^3He$, and $\rm ^4He$ in Au+Au collisions at BES-II energies of $\sqrt{s_{\rm NN}}$ = $3-27$ GeV. The uncertainties on yields and ratios in BES-II are reduced by a factor of approximately 3-5 compared to BES-I. The thermal model overestimates the $N_{^3\mathrm{He}}/N_p$ and $N_{^4\mathrm{He}}/N_p$ ratios, with discrepancies increasing toward lower collision energies and reaching up to 50%. In contrast, the coalescence calculation provides a better description for nuclei with $A \leq 3$, while underpredicting $^4\mathrm{He}$.

Speaker: Yixuan Jin (Central China Normal University)

Parallel 3

34 Inclusive Jpsi production and the Jpsi energy-correlator in high-energy pp collisions

In this talk, we will present the inclusive J/ψ production in proton-proton collisions at \sqrt{s}= 5.02, 7 and 13 TeV. A quantitative analysis of the relative contributions for different production mechanisms (NRQCD, cluster collapse, and non-prompt) in the inclusive J/ψ production, as well as the energy and rapidity dependence of these contributions will be shown. We will also discusse the effect of the hadronisation process on the J/ψ-hadron energy correlator. These works have been published in Phys. Rev. C 109, 035201 (2024), Phys. Rev. C 113, 045210 (2026), and Phys. Rev. D 113, 054038 (2026).

Speaker: Wenchao(文超) Zhang(张) (陕西师范大学)

35 Extracting In-Medium Heavy Quark Potentials via Quarkonia with Deep Learning

We use Bayesian inference with deep-learning surrogate models to quantitatively extract the in-medium heavy quark (HQ) potential from bottomonium nuclear modification factors ($R_{AA}$) measured in Pb--Pb collisions at $\sqrt{s_{NN}}=5.02$ and $2.76$ TeV and Au--Au collisions at $\sqrt{s_{NN}}=200$ GeV. The real and imaginary parts of the potential are parametrized and embedded in a time-dependent Schr\"odinger equation for the evolution of $b\bar b$ dipoles in hydrodynamic QCD media. To accelerate the inverse problem, we train collision-system-specific CNN surrogate models that map the potential parameters to bottomonium $R_{AA}$ observables. The training data are generated from Schr\"odinger-model calculations and augmented using Principal Component Analysis (PCA) and Gaussian Process Regression (GPR). We then perform a joint Stochastic Gradient Langevin Dynamics (SGLD) posterior sampling of the potential parameters using all available RHIC and LHC bottomonium data. Within the present parametrization and hydrodynamic background, the real part of the in-medium potential remains close to the vacuum Cornell form, corresponding to a relatively weak screened Debye mass across RHIC to LHC energies. By contrast, the imaginary part is more strongly constrained by the data and provides the dominant contribution to bottomonium suppression from RHIC to LHC energies.

Speaker: baoyi chen (Tianjin University)

36 Nuclear modification of energy-energy correlators inside jets in heavy-ion collisions

Energy-energy correlator (EEC) is an excellent jet substructure observable owning to its strong sensitivity to jet physics at different scales. Using a hybrid Pythia 8 + LBT framework, we perform a complete realistic simulation on medium modification of heavy and light flavor jet EEC in heavy-ion collisions. A clear flavor hierarchy is observed for jet EEC in both vacuum and QGP due to the mass effect~[1]. Recently, both CMS and ALICE collaborations have observed a significant nuclear modification of jet EECs in heavy-ion collision relative to pp colisions. To interpret those measurements, we refine the modular description of jet production and evolution inside the quark-gluon plasma by matching vacumm parton shower to in-medium parton transport at a medium scale of $Q_{\mathrm{M}}$ = 2 GeV. Within this updated framework, we present numerical results for PbPb to pp ratios of energy-energy correlators inside jets for different cone size and transverse momentum intervals, which provide a good description of experimental data from both CMS and ALICE collaboration~[2]. Our study indicates that the small-angle enhancement is mainly driven by jet selection bias, the intermediate-angle suppression by parton energy loss, and the large-angle enhancement by medium-induced radiation and medium response. We further predict PbPb to pp ratios for $D$-tagged jets and $B$-tagged jets, finding that both medium suppression and enhancement becomes weaker due to the mass effect on jet-medium interactions. These results confirm jet EECs as a differential probe of jet modification in the QGP.

References:
[1] Wen-Jing Xing, Shanshan Cao, Guang-You Qin, and Xin-Nian Wang, Phys.Rev.Lett. 134 (2025) 5, 052301
[2] Wen-Jing Xing, Shanshan Cao, Guang-You Qin, and Xin-Nian Wang, in preparation.

Speaker: Dr Wen-Jing Xing (University of South China)

37 Non-perturbative heavy quark dynamics in a QGP with arbitrary magnetic field

Heavy quark (HQ) momentum ($\kappa$) and spatial diffusion ($D_s$) coefficients are computed in a non-perturbative thermal QCD medium in the presence of a background magnetic field of arbitrary strength. Both perturbative (Yukawa) and non-perturbative (string) effects are incorporated via the in-medium HQ potential, obtained from the resummed
gluon propagator ($D_{\mu\nu}$). To that end, an ansatz is used for the non-perturbative gluon propagator such that it reproduces the string term in the Cornell potential (in vacuum). The heavy quark self energy is then calculated using $D_{\mu\nu}$, and the momentum diffusion coefficients ($\kappa_L$, $\kappa_T$) obtained therefrom. It is observed that the $\kappa$ are anisotropic even in the static heavy
quark limit ($\vec{v}\to 0$), with the magnetic field direction defining the axis of anisotropy. This anisotropy originates from
restrictions on longitudinal momentum diffusion in the gluon spectral function, and naturally leads to two spatial
diffusion coefficients ($D_s^L$ , $D_S^T$ ). However, the ratio of the string to Yukawa contribution in $\kappa$ is found to be isotropic, so that, $\kappa_L^Y\neq \kappa_T^Y\neq \kappa_L^s\neq\kappa_T^s$, but $\frac{\kappa_L^s}{\kappa^Y_L}=\frac{\kappa_T^s}{\kappa^Y_T}$. Non-perturbative (string) contributions are found to be dominant at low temperatures. These results can serve as a more consistent input for Langevin based calculations of the heavy quark directed flow ($v_1$) at RHIC and LHC energies.

Speaker: Debarshi Dey (Shanghai Jiao Tong University)

38 D0-Ds+ Elliptic-Flow Splitting under Event-Shape Engineering: A Probe of Sequential Charm Hadronization

Recent work has proposed sequential hadronization of open-charm hadrons in the quark-gluon plasma, wherein more tightly bound species such as Ds+ form earlier near 1.2Tc and D0 forms later at Tc. That work showed that this mechanism naturally reverses the sign of the D0 − Ds+ elliptic-flow splitting ∆v2 ≡ v2(D0) − v2(Ds+) relative to the conventional simultaneous baseline. In this work, we demonstrate that event-shape engineering (ESE) provides a sharper discrimination between the two pictures than inclusive measurements alone. By selecting large-q2 and small-q2 events in 0–10% and 30–50% centrality classes in Pb–Pb collisions at √sNN = 5.02 TeV, we show that the geometry-driven enhancement of charm-meson v2 can be separated from the hadronization-time response: the positive ∆v2(D0 − Ds+) in the sequential scenario grows systematically with q2,while the corresponding response slope χ reveals a species-dependent hierarchy χ(D0) > χ(Ds+) that is robust against the overall flow normalization and absent in the simultaneous baseline. In the simultaneous case, the splitting is near zero or negative and does not follow the same geometry scaling. Notably, the semi-central 30–50% class emerges as the optimal window, because the non-monotonic interplay between QGP lifetime and initial eccentricity maximizes the late-stage flow conversion. The Ds+/D0 yield ratio and its q2 double ratio remain close to unity, confirming that the splitting is a dynamical flow effect rather than a chemical yield modification. These results establish ∆v2(D0 − Ds+) and the response slope χ under ESE as complementary differential probes of the space-time structure of charm hadronization near the QCD transition temperature.

Speaker: YuJie Huang

39 Measurement of $J/ \psi$ photoproduction in ultra-peripheral Ru+Ru and Zr+Zr collisions at 200 GeV with the STAR experiment

In ultra-peripheral collisions (UPCs), coherent J/$\psi$ photoproduction provides a sensitive probe of the nuclear gluon distributions. The STAR collaboration has reported differential measurements of photoproduced J/$\psi$ in Au+Au UPCs, providing important constraints on nuclear gluon structure and sub-nucleonic fluctuations in heavy nuclei. Compared with Au+Au collisions, isobaric systems ($^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr) feature smaller nuclear sizes and different nuclear structures. Measurements in these collision systems provide a unique opportunity to investigate the system-size dependence of coherent J/$\psi$ photoproduction and nuclear modifications of the gluon distribution.

In this talk, the first cross section measurements of coherent $J/\psi$ photoproduction in ultra-peripheral Ru+Ru and Zr+Zr collisions at $200$ GeV will be presented. Differential cross sections are measured as functions of rapidity and forward neutron multiplicity. A significant suppression of coherent $J/\psi$ photoproduction relative to the Impulse Approximation is observed in both collision systems, indicating strong nuclear shadowing effects. By correcting for the photon flux, photon--nucleus cross sections are extracted at an average photon-nucleon center-of-mass energy of $25$ GeV. Together with previous Au+Au measurements, the extracted cross sections are found to follow a power-law dependence on the nuclear mass number ($A$): $\sigma(\gamma A \rightarrow J/\psi A)\propto A^{\alpha}$ with $\alpha = 0.95 \pm 0.08$. These measurements provide new constraints on nuclear gluon distribution and the system-size dependence of nuclear shadowing effects.

Speaker: Zengzhi Li (South China Normal University)

Parallel 4

40 Semi-inclusive jet mass measurements in Zr+Zr and Ru+Ru collisions at $\sqrt{s_{\text{NN}}} = 200$ GeV with STAR

In relativistic heavy-ion collisions, jet substructure observables provide unique access to the interactions between energetic partons and the hot, dense QCD medium known as the Quark–Gluon Plasma (QGP). Among them, the jet invariant mass ($M_{\mathrm{jet}}$) is particularly sensitive to parton virtuality evolution and the pattern of final-state radiation. However, measurements of jets with low jet transverse momentum ($p_{\mathrm{T,jet}}$) are significantly limited due to the large combinatorial background originating from the underlying events of heavy-ion collisions. To address this challenge, we employ the semi-inclusive approach by analyzing jets recoiling from a high-$p_{\mathrm{T}}$ trigger hadron ($7 In this talk, we present semi-inclusive $M_{\mathrm{jet}}^2$ distributions in Zr+Zr and Ru+Ru collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV measured with the STAR detector, and introduce a novel 2-dimensional semi-inclusive methodology as a function of $(p_{\text{T,jet}}, M_{\text{jet}}^2)$. Jets are reconstructed using the anti-$k_{\mathrm{T}}$ algorithm with jet resolution parameters ($R=0.2$ and $0.4$), and are selected in the recoil region ($|\pi-\Delta\phi|<\pi/4$) with respect to the trigger hadron. The comparison of the fully corrected $M_{\mathrm{jet}}^2$ distributions between the 0--10\% and 60--80\% centrality classes is performed to investigate modifications to the peak position and shape of the $M_{\mathrm{jet}}^2$ distributions. Such modifications serve as sensitive probes of medium-induced modifications to parton virtuality evolution.

Speaker: Jeongmyung Kang (Sejong university)

41 Jet quenching and its substructure dependence due to color decoherence

Motivated by color coherence and decoherence effects in the QCD medium, we propose a theoretical framework that combines vacuum-like emissions and medium-induced radiation to study jet quenching and its dependence on jet cone sizes and substructure. In our approach, a jet produced at a hard scale $Q$ first undergoes vacuum-like evolution, as described by the well-established generating-function method in the double logarithmic approximation. These vacuum-like emissions generate subjets at an infrared momentum scale $Q_0$. Each subjet then experiences medium-induced energy loss as described by the BDMPS-Z formalism. By modeling the QCD bulk medium using OSU (2+1)-dimensional viscous hydrodynamics and treating $Q_0$ together with the jet-quenching parameters at the initial proper time of the hydrodynamic evolution as free parameters, our approach provides a very good description of the inclusive jet modification factor $R_{AA}$ for large-radius jets and its dependence on jet substructure in 0-10% PbPb collisions at $\sqrt{s_{NN}} = 5.02~\rm{TeV}$, as measured by the ATLAS experiment.

[1] X.-P. Duan, L. Chen, G.-L. Ma, C. A. Salgado, and B. Wu, arXiv:2603.22014.
[2] X.-P. Duan, L. Chen, G.-L. Ma, C. A. Salgado, and B. Wu, JHEP 02 (2026) 123.
[3] X.-P. Duan, L. Chen, G.-L. Ma, C. A. Salgado, and B. Wu, Phys. Rev. D 112, 094022 (2025).

Speaker: Xiang-Pan Duan (Central China Normal University)

42 Jet anisotropy in polarized scattering

In this talk, we study the azimuthal anisotropy of the back-to-back lepton-jet production in polarized lepton-proton collisions.
In particular, we provide the theoretical origins for the dependencies on $\phi_q - \phi_J$ from a factorization formalism derived within the soft-collinear effective theory (SCET) framework.
We further present numerical results for the polarized azimuthal anisotropies associated with the Sivers and worm-gear functions with Electron-Ion Collider kinematics.
Our findings reveal that the presence of the observed jet introduces nontrivial azimuthal dependence into the soft functions, generating higher-harmonic patterns that can discernibly alter the conventional asymmetries and thus must be carefully accounted for in any precision extraction of polarized TMD PDFs.

Speaker: Yiyu Zhou

43 A resolution-based framework for coherent and decoherent jet quenching at next-to-leading order

In high-energy heavy-ion collisions, high-energy jets produced by initial hard scatterings interact with the quark–gluon plasma (QGP) and lose energy during their propagation. A single jet may contain multiple partons, which can interact with the QGP either coherently or decoherently. Current Pb+Pb collision experiments have reached a center-of-mass energy of 5.02 TeV, and jet transverse momentum reaches up to 1 TeV, where decoherence effects become non-negligible.

Based on the NLO pQCD parton model and the high-twist energy loss model, this work defines the resolution scale $Q_\mathrm{pair}$ between two partons as their invariant mass and introduces a medium resolution scale $Q_{\rm med}$.Additionally, we introduce a coherence intensity $I(Q_{\rm pair})$ to quantify the fraction of coherent energy loss.

By comparing with experimental data on inclusive jets, reclustered jets, soft-drop $r_{\rm g}$, and jet mass from Pb+Pb collisions at 5.02 TeV, we demonstrate the effectiveness of this method in calculating high-energy jet energy loss.

Speaker: Peng-Hui Hu (Central China Normal University)

44 System- and Cone-Size Dependence of Dijet Quenching and Energy-Energy Correlators in Pb–Pb and O–O Collisions

Jet quenching provides a powerful probe of the properties and space-time structure of the quark-gluon plasma (QGP) created in high-energy nuclear collisions. In particular, the dependence of jet observables on the jet cone size offers direct sensitivity to the angular redistribution of energy induced by medium-modified parton showers and medium response. In this work, we investigate the cone-size dependence of dijet quenching in both Pb–Pb and O–O collisions within the Linear Boltzmann Transport (LBT) model.

We calculate the dijet momentum imbalance $x_J=p_{\mathrm{T},2}/p_{\mathrm{T},1}$ and the nuclear modification factor $R_{AA}$ for different jet cone sizes, and systematically compare their medium modifications in Pb–Pb and O–O collisions. The comparison between the two collision systems allows us to quantify the system-size dependence of parton energy loss and examine how the finite size of the QGP affects the redistribution of energy inside and outside the reconstructed jet cone.

Furthermore, we study the energy-energy correlator inside jets to resolve the angular structure of medium-induced modifications and to investigate the respective contributions from medium-induced radiation and medium response. These results provide a unified picture of the cone-size and system-size dependence of dijet quenching, and offer new constraints on the mechanisms of jet-medium interactions in QGP systems ranging from heavy to light nuclei.

Speaker: Prof. Shanshan Cao (Shandong University)

45 Jet-Induced Medium Response in Heavy-Ion Collisions: From Flow-Distorted Wakes to Fast Generative Modeling

Energy and momentum deposited by energetic partons in the quark-gluon plasma (QGP) generate a Mach-cone-like jet-induced medium response consisting of a propagating wake front and a diffusion wake. In realistic heavy-ion collisions, this response evolves in a nonuniform and expanding medium and is therefore distorted by the density gradient and hydrodynamic flow. Using the coupled Linear Boltzmann Transport and hydrodynamic (CoLBT-hydro) model, we show that the elliptic geometry and elliptic flow in non-central collisions lead to an azimuthally dependent broadening of the jet wake. We propose differences between in-plane and out-of-plane jet-hadron correlations, including their azimuthal dependence and rapidity asymmetries, as observables of the broadening of the wake front and the deepening of the diffusion wake. Their sensitivity to the shear viscosity provides a possible means of constraining the transport properties of the QGP.

To enable more extensive studies of such medium responses, we further train a Flow Matching generative model using CoLBT-hydro $\gamma$-jet events in $0$--$10\%$ Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02~\mathrm{TeV}$. Conditioned only on the initial spatial and momentum information of the photon and jets, the model generates the final-state soft-hadron spectrum $\frac{\mathrm{d}^{3}N} {\mathrm{d}p_T\,\mathrm{d}\eta\,\mathrm{d}\phi}.$ It reproduces the statistical properties of both the wake front and the diffusion wake while achieving an acceleration of approximately six orders of magnitude relative to full CoLBT-hydro simulations. These results provide both experimentally accessible observables and an efficient generative framework for studying jet-induced medium response in heavy-ion collisions.

Speaker: 开燚 吴 (CCNU)

Coffee Break

Parallel 1

46 Study of pT-Differential Radial Flow Fluctuations Using v0(pT) in Au+Au Collisions at sqrt(sNN) = 7.7-200 GeV at RHIC

Radial flow is conventionally studied through transverse-momentum ($p_{T}$) spectra and blast-wave model analyses, which provide information on the average collective expansion and kinetic freeze-out properties of the system. In contrast to the extensively studied anisotropic-flow coefficients $v_{2}$ and $v_{3}$, the $p_{T}$-differential fluctuations of radial flow remain largely unexplored. The recently proposed observable $v_{0}(p_{T})$ provides direct sensitivity to $p_{T}$-differential radial-flow fluctuations~\cite{Schenke_v0,Tribhuban_v0}. The RHIC Beam Energy Scan provides a unique opportunity to investigate how $p_{T}$-differential radial expansion and its event-by-event fluctuations evolve across a broad region of the QCD phase diagram.

In this work, we present measurements of $v_{0}(p_{T})$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7--200 GeV with the STAR experiment at RHIC. The beam-energy and centrality dependence of $v_{0}(p_{T})$ is studied for charged hadrons as well as identified pions, kaons, and protons.Particular emphasis is placed on the slope of the $p_{T}$ dependence of $v_{0}(p_{T})$ and the characteristic $p_{T}$ at which $v_{0}(p_{T})$ changes sign, as these features are sensitive to the strength and fluctuations of radial flow~\cite{Model_v0}. A blast-wave model incorporating event-by-event fluctuations is simultaneously fitted to the proton, kaon, and pion $v_{0}(p_{T})$ data to extract the radial-flow velocity, kinetic freeze-out temperature ($T_{\mathrm{kin}}$), and their event-by-event fluctuations. The extracted parameters provide a quantitative characterization of the beam-energy evolution of the average radial expansion and kinetic freeze-out conditions, as well as their fluctuations, thereby enabling us to assess the relative contributions of radial-flow and freeze-out fluctuations to the observed $v_{0}(p_{T})$ behavior.

\begin{thebibliography}{99}

\bibitem{Schenke_v0}
Björn Schenke, Chun Shen, and Derek Teaney. \textit{Phys. Rev. C 102} (2020), p. 034905.
\bibitem{Tribhuban_v0}
Tribhuban Parida, Rupam Samanta, and Jean-Yves Ollitrault. \textit{Phys. Lett. B 857} (2024), p. 138985.
\bibitem{Model_v0}
Syed Afrid Jahan, Hendrik Roch, and Chun Shen. arXiv:2507.11394 (2025).
\end{thebibliography}

Speaker: Bappaditya Mondal(for STAR collaboration) (NISER, India)

abstract_ATHIC_Bappa_abstrct_2026_d7.pdf

47 Collective Flow of Strange and Multistrange Hadrons with STAR

Directed flow ($v_1$) and elliptic flow ($v_2$) provide complementary probes of the equation of state, degrees of freedom, and collective dynamics of the produced medium. Here, we present STAR measurements of collective flow for identified strange and multistrange hadrons in heavy-ion collisions at RHIC.

Using high-statistics data from the STAR Beam Energy Scan Phase-II (BES-II) fixed-target and collider programs, together with previously recorded higher-energy Au+Au data, we investigate strange-hadron collective flow over a broad range of collision energies. In Au+Au collisions at $\sqrt{s_{NN}}=3.0$–$4.5$~GeV, directed-flow measurements, including negative directed-flow slopes for low-$p_T$ kaons, provide information on spectator shadowing and collision dynamics. Elliptic-flow ($v_2$) measurements over $\sqrt{s_{NN}}=3.0$–$19.6$~GeV probe the collision-energy evolution of number-of-constituent-quark (NCQ) scaling and the onset of partonic collectivity. Approximate NCQ scaling, with NCQ-scaled baryon-to-meson ratios close to unity, is observed for both particles and antiparticles at $\sqrt{s_{NN}}=7.7$–$19.6$~GeV. Together with the observed mass ordering, these observations are consistent with collective expansion prior to hadronization. As a complementary probe of strange-hadron collectivity, we further present the $p_T$-differential radial-flow fluctuation observable, $v_0(p_T)$, for strange and multi-strange hadrons from $\sqrt{s_{NN}}=11.5$ to $200$~GeV.
Comparisons with transport and hydrodynamic model calculations provide additional constraints on the collision-energy dependence of collective expansion and help interpret its implications for the QCD phase structure.

Speaker: Guoping Wang (Central China Normal University)

48 Beyond Quadrupole Deformation: Resolving Multipolarity and Diffuseness Degeneracies in Relativistic Heavy-Ion Collisions

Relativistic heavy-ion collisions provide a unique avenue to image nuclear structure by converting initial spatial geometry into the collective expansion of the Quark--Gluon Plasma (QGP). While the quadrupole deformation ($\beta_2$) sits at the center of this paradigm as the primary driver of initial geometry, a complete understanding of nuclear shape requires extending this framework to include triaxiality ($\gamma$), higher-order multipoles such as hexadecapole deformation ($\beta_4$), and the nuclear surface diffuseness ($a$). Connecting these fundamental parameters, however, introduces severe physical challenges: three-dimensional triaxial fluctuations redistribute geometric information unequally across final-state species, higher-order hexadecapole shapes violate conventional multipole scaling rules, and intrinsic shape deformation exhibits a strong degeneracy with the nuclear skin diffuseness. Using event-by-event relativistic hydrodynamic and initial-state simulations, I discuss how the QGP dynamics both compound and resolve these connections. I show that species-dependent differential responses preserve robust maps of quadrupole and triaxial shapes, while higher-order nonlinear mode coupling cleanly isolates intrinsic hexadecapole topologies. Finally, I discuss the shape--diffuseness degeneracy by identifying dynamic correlation strategies that isolate the surface profile independently of deformation and microscopic initial-state uncertainties.

Speaker: Hadi Mehrabpour

49 Disentangling the neutron skin of $^{48}$Ca from nuclear radius effects through $^{48}$Ca+$^{48}$Ca and $^{48}$Ti+$^{48}$Ti flow observables

The thickness of the neutron skin ($\Delta r_{np}$) in $^{48}$Ca remains uncertain, with parity‑violating electron scattering (CREX) and ab initio calculations favoring a thin skin while energy density functionals prefer larger values. Heavy‑ion collisions at relativistic energies can probe the skin through its geometric imprint on the quark‑gluon plasma, but a thicker skin also increases the effective nuclear matter radius, creating a size–skin degeneracy that complicates interpretation. We resolve this by systematically comparing $^{48}$Ca+$^{48}$Ca and $^{48}$Ti+$^{48}$Ti collisions at $\sqrt{s_{NN}}=5.02$ TeV using the AMPT model with string melting. Three neutron‑skin configurations are implemented for $^{48}$Ca with their limits defined by the CREX upper and lower bound and a zero-skin ($\Delta r_{np}=0$) baseline, together with a size-controlled $^{48}$Ca reference with a matched proton radius that isolates the skin effect from the size effect. We find that the neutron skin is a purely geometric perturbation: the hydrodynamic response coefficients are unchanged, and all flow modifications are inherited from the initial geometry. First‑moment observables exhibit only modest sensitivity to $\Delta r_{np}$, while second‑moment quantities such as variances, linear response correlators, event‑plane alignment, and correlation between shape and size, are substantially amplified. The covariance between elliptic flow and mean transverse momentum fluctuations emerges as the single most sensitive probe, enhanced by up to 25% in the initial state and 12% in the final state for the CREX upper bound. Our results establish that isobaric $^{48}$Ca/$^{48}$Ti collisions at the LHC, combined with multi-observable analysis targeting second-moment and geometry-flow correlators, provide a clean and high-precision pathway to constrain the neutron skin of $^{48}$Ca independently of nuclear scattering experiments.

Speaker: Abhisek Saha (Peking University)

50 Measurement of triangular flow of identified hadrons in Au+Au collisions from the RHIC Beam Energy Scan program with STAR

The triangular flow coefficient ($v_{3}$) is the third term in the Fourier expansion of the azimuthal distribution of particles produced in heavy-ion collisions. A non-zero $v_{3}$ arises from event-by-event fluctuations in the positions of participant nucleons within the collision zone. Higher order flow coefficients, particularly $v_{3}$ and higher harmonics, exhibit enhanced sensitivity to the transport properties of the created medium, including the shear viscosity-to-entropy density ratio ($\eta/s$) [1].

In this talk, we present the measurement of $v_{3}$ for identified hadrons in Au+Au collisions from the RHIC Beam Energy Scan (BES) by the STAR experiment, covering $\sqrt{s_{NN}} = 7.7$ to $62.4$ GeV. We will show the transverse momentum ($p_{T}$), centrality, and collision energy dependence of $v_{3}$, which serve as important observables for constraining the $\eta/s$ of the medium. Additionally, we will present the number-of-constituent-quark (NCQ) scaling and the coalescence sum rule for $v_{3}$, which may provide insight into the properties of the medium and the possible onset or disappearance of partonic collectivity.

[1] Björn Schenke, Sangyong Jeon and Charles Gale, Phys. Rev. C. 85, 024901 (2012).

Speaker: Dr Prabhupada Dixit (Fudan university)

v3_abstract_final.pdf

Parallel 2

51 Thermodynamic signatures do not uniquely identify deconfinement in neutron stars

Neutron-star measurements constrain the
pressure–energy-density relation but leave the micro-
scopic composition of dense matter unresolved. A poly-
tropic index Γε < 1.75 and sound speed C2
s = 1/3 have
both been used as signatures of quark degrees of free-
dom. We test these interpretations by calibrating a nu-
cleonic reference domain in the (Γε, P/Pfree) plane. A
Taylor metamodel conditioned on current mass, radius
and tidal data defines this domain, whose boundary sta-
bilizes when fourth-order density terms are retained. Its
extension below Γε = 1.75 shows that the threshold can
also be reached by purely nucleonic matter. We next gen-
erate a broad set of observationally admissible, smooth
single-branch EOSs using neural networks and symbolic
regression. Of these trajectories, 59.8% remain entirely
within the nucleonic domain and 88.6% remain inside
it over at least 90% of the sampled density interval.
Constrained minimization over the admissible EOS class
gives minEadm maxn c2 s = 0.38, requiring the sound speed
to exceed the conformal value 1/3 somewhere within this
class. Such an exceedance, like a sound-speed maximum
or a low polytropic index, constrains the evolution of
stiffness but does not establish deconfinement. The ref-
erence domain thus tests compatibility with a nucleonic
null hypothesis while leaving the identity of any alterna-
tive phase open.

Speaker: Yong-Liang Ma (Nanjing University)

52 A Bayesian Machine Learning Approach to Centrality Determination in Heavy-Ion Collisions

In relativistic heavy-ion collisions, the collision centrality is conventionally determined by sorting events into percentile bins of charged-particle multiplicity.
The procedure is applied to a stochastic relation between multiplicity and initial geometry.
The associated finite volume fluctuation is therefore irreducible and introduce an inevitable uncertainty, impacting many centrality-dependent measurements.
We present a machine learning approach to centrality determination: the Inference-driven Participant Determination (IPD) method.
It replaces the hard multiplicity cut with Bayesian probabilistic inference.
The method uses the Monte-Carlo Glauber (MCG) model as a prior and a product of negative binomial distributions as the likelihood, yielding an event-by-event posterior distribution of participant numbers ($N_{\rm part}$) and binary collisions ($N_{\rm coll}$) directly from final-state charged-particle multiplicities.
Unlike supervised learning approaches, IPD requires no transport-model training and is directly applicable to experimental data.
A self-consistent closure test using a UrQMD-MCG hybrid model at $\sqrt{s_{\rm NN}} = 19.6$~GeV demonstrates that the method produces well-calibrated posteriors with
negligible bias.
The IPD-based centrality yields $\sigma(N_{\rm part})$ distributions that are 11\% to 46\% narrower than those from conventional multiplicity-based classification.
This method suppresses volume fluctuation effects, allowing cleaner measurements with less affected by contamination from volume fluctuations.
The improvement in centrality purity is robust across $\sqrt{s_{\rm NN}} = 3.0$, 7.7, and 19.6~GeV, covering the RHIC Beam Energy Scan range.
The IPD framework is general and can be adapted to centrality determination in other heavy-ion experiments, such as CBM and CEE.

Speaker: Yige Huang (IMP, CAS)

53 Investigating jet quenching with jet-like dihadron correlations in light-Ion systems (pO, OO, Ne–Ne) at ALICE

Heavy-ion collisions are studied to probe hot, dense nuclear matter, known as the quark–gluon plasma (QGP). While flow-like signatures observed in pp and p–Pb collisions at the LHC suggest that QGP-like behavior may emerge even in small systems, jet quenching has so far remained unobserved in such collisions. To better understand the transition between small and large collision systems, the LHC has recently collected light-ion collision data. We present jet-like dihadron correlation measurements in light-ion (pO, O–O and Ne–Ne) collisions at $\sqrt{s_{\mathrm{NN}}}=5.36~\mathrm{TeV}$ recorded by the ALICE Collaboration and compared to the pp collision system. The width of the near-side jet-fragmentation correlation peak and fragmentation yields are studied across these systems. The results are also compared with model calculations including and excluding jet-quenching scenarios.

Speaker: Kyeongho Lee (Jeonbuk National University)

54 Probing signals of the Chiral Magnetic Effect from the 2+1 PNJL model

We study the Chiral Magnetic Effect (CME) in relativistic heavy-ion collisions using charge fluctuations and their correlations generated in the early stages of the collision. Employing the 2+1 flavor Polyakov-loop-extended Nambu–Jona-Lasinio (PNJL) model, we compute the charge separation associated with the CME. A central challenge in interpreting these correlations experimentally is contamination from background effects unrelated to the CME. To address this, we probe the system at finite charge chemical potential, which comes from charge fluctuations from sources independent of the CME. We find that the charge separation induced by a finite charge chemical potential differs from that arising from the CME itself. This suggests that our approach offers a route toward understanding contaminants of the CME signals in heavy-ion collision.

Speaker: Somdeep Dey (University of Hyderabad)

ATHICabstract.pdf

55 Probing Baryon-rich QCD Matter with Deuteron Cumulants and Proton–deuteron Mixed Cumulants in Au+Au Collisions at STAR

The deuteron carries baryon number two and is abundantly produced in the baryon-rich matter created in heavy-ion collisions. Its number fluctuations can provide insight into QCD matter at high baryon density and may be sensitive to critical-point physics. Since deuterons are formed from nucleons, their fluctuations are closely connected to baryon-density fluctuations and can complement conserved-charge cumulant measurements. Their dependence on rapidity acceptance can also help probe the range of the underlying correlations. In addition, deuteron cumulants and proton–deuteron correlations provide useful information on the production mechanism of light nuclei in heavy-ion collisions.

We report measurements of cumulants up to fourth order, factorial cumulants, and their ratios for deuteron number distributions, together with proton–deuteron mixed cumulants, in Au+Au collisions at $\sqrt{s_{NN}} = 3.0$ GeV FXT to 7.7 GeV BES-II collider energy at STAR. These measurements reach the high-$\mu_B$ region of the RHIC beam energy scan. Deuterons are identified using the Time Projection Chamber and Time-of-Flight detectors within $0.8 < p_T \,(\mathrm{GeV}/c) < 4.0$. The centrality and rapidity-acceptance dependence of deuteron cumulants and proton–deuteron mixed cumulants will be presented after corrections for detector efficiency and centrality bin-width effects. The results will be compared with thermal and coalescence model calculations, and their implications for baryon-number dynamics and the QCD phase diagram at high baryon density will be discussed.

Speaker: Debasish Mallick (For the STAR Collaboration) (Central China Normal University)

ATHIC2026_Abst_DM_v3.pdf

Parallel 3

56 Production of psi(4040), psi(4160) and psi(4415) mesons in ultrarelativistic heavy-ion collisions

Production of $\psi(4040)$, $\psi(4160)$ and $\psi(4415)$ mesons in
ultrarelativistic heavy-ion collisions
Xiao-Ming Xu
Department of Physics, Shanghai University, Baoshan, Shanghai 200444, China

$\psi(4040)$, $\psi(4160)$ and $\psi(4415)$ mesons are higher charmonia that
can be individually interpreted as the $3 ^3S_1$, $2 ^3D_1$ and $4 ^3S_1$
quark-antiquark states. In ultrarelativistic heavy-ion collisions the three
charmonia created in initial nucleus-nucleus collisions are dissolved in
quark-gluon plasmas because their dissociation temperatures are $0.97T_{\rm c}$,
$0.95T_{\rm c}$ and $0.87T_{\rm c}$, respectively, where $T_{\rm c}$ is the
critical temperature. However, they can be produced by quark
interchange between two colliding charmed mesons in hadronic matter. From the
three charmonia we can thus study hadronic matter in a new way. Therefore, we
suggest the production of $\psi (4040)$, $\psi (4160)$ and $\psi (4415)$ as
probes of hadronic matter that results from the quark-gluon plasma created in
ultrarelativistic heavy-ion collisions. We have proposed a model to study
the production of the three charmonia in Pb-Pb collisions at the Large Hadron
Collider. Seventy-two reactions of charmed mesons are taken into account.
From our work we have suggested measurements of $\psi (4040)$, $\psi (4160)$
and $\psi (4415)$ mesons in Pb-Pb collisions at the Large Hadron Collider.
This is a new experimental goal! Details can be found in the three papers:
L.-Y. Li, X.-M. Xu and H. J. Weber, Phys. Rev. D105 (2022) 114025; W.-X. Li,
X.-M. Xu and H. J. Weber, Eur. Phys. J. C81 (2021) 225; S.-N. Xu and X.-M. Xu,
Chin. Phys. C49 (2025) 024103.

Speaker: Prof. Xiao-Ming Xu (Shanghai University)

57 (Anti-)(Hyper-)Nuclei in High-Energy Nuclear Collisions: Production, Structure, and Polarization

In the present talk, I will review recent progress on (Anti-)(Hyper-)Nuclei production, structure, and polarization in High-Energy Nuclear Collisions

Speaker: kai-jia sun (fudan university)

58 Transverse-momentum-differential azimuthal correlation of heavy-flavor electron-muon pairs in pp collisions at $\sqrt{s}$=13.6 TeV with ALICE

In heavy-ion collisions, heavy quarks serve as sensitive probes of the quark–gluon plasma (QGP), as they traverse and interact with the constituents of the medium throughout its entire evolution. In proton–proton (pp) collisions, the study of their production offers stringent tests of perturbative quantum chromodynamics (pQCD) calculations and serves as an essential baseline for the interpretation of heavy-ion collision data. The azimuthal correlation of electrons and muons from heavy-flavor hadron decays is sensitive to the heavy-flavor production processes and, in heavy-ion collisions, to in-medium energy loss. Compared to electron–electron or muon–muon pairs, electron–muon pairs have the advantage of strongly suppressing backgrounds from electromagnetic processes such as Drell‒Yan production and resonance decays. The ALICE detector offers the unique opportunity of a large rapidity gap between the electron and muon acceptance regions. This feature suppresses near-side jet correlations and gives access to long-range correlations, offering new sensitivity to multiparton interactions and collective effects across collision systems of different size, from pp to Pb–Pb.
In this contribution, we present the status of the measurement of the azimuthal-correlation of heavy-flavor decay electron–muon pairs in pp collisions at $\sqrt{s}$ = 13.6 TeV with ALICE. Background-subtracted correlations, obtained with a data-driven method to remove misidentified hadrons, residual photonic electrons, and light-hadron decay muons, are shown in intervals of the electron transverse momentum.

Speaker: Shunsuke Kurita (Hiroshima University)

59 Bottomonium production within the potential model in Schroedinger and Lindblad frameworks

Bottomonium bound states serve as invaluable probes of the quark-gluon plasma (QGP) in relativistic heavy-ion collisions, owing to their negligible thermal production and non-relativistic nature that allows a theoretical description via potential non-relativistic QCD (pNRQCD). However, recent lattice QCD calculations of the in-medium bottomonium potential have yielded qualitatively distinct results---differing in the relative strengths of color screening and singlet-to-octet transitions---which motivates a data-driven approach to constraining the potential from experimental measurements.

We first perform a Bayesian analysis to extract the in-medium bottomonium potential by numerically solving the time-dependent Schroeodinger equation and comparing the resulting nuclear modification factors ($R_{AA}$) of $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ with LHC data. The Schroeodinger framework exhibits two competing scenarios by displaying the posterior distribution with a bimodal structure, which may be insufficient for a definitive determination of the potential.

The Schoeodinger framework does not account for the octet-to-singlet regeneration, which has been recently suggested important in bottomonium production. We go beyond the pure-state description and investigate bottomonium production within the density-matrix description. The $b\bar{b}$ density matrix, comprising both color-singlet and color-octet blocks, evolves according to a Lindblad master equation where the collapse operators are directly matched to the imaginary potential from lattice QCD, thereby naturally incorporating quantum regeneration of singlet states from octet configurations. It is shown that regeneration is more important when a potential with a larger imaginary part, i.e., stronger transitions between singlet and octet states, is used. This indicates that the Bayesian analysis based on the Lindblad framework should be taken into consideration.

References:
1. Shuhan Zheng, B. Chen, X. Du and S. Shi. Phys. Rev. C b8n3-yrq1.
2. Shuhan Zheng and S. Shi. ArXiv: 2607.06191.

Speaker: 纾寒 郑 (清华大学物理系)

60 Investigation of the \texorpdfstring{$N\Omega$}{NOmega} dibaryon from lattice QCD at the physical point

The $N\Omega$ system is a promising candidate for a dibaryon bound state. To enable a direct comparison between lattice QCD and experiment, we calculate the $^5S_2$ $N\Omega$ interaction in $(2+1)$-flavor lattice QCD at the physical point ($m_\pi\simeq137.1$ MeV and $m_K\simeq501.8$ MeV) with the time-dependent HAL QCD method. Because the coupling to the $D$-wave octet-octet channels is weak, a clean single-channel analysis is possible. We find that the $^5S_2$ $N\Omega$ potential is fully attractive and that a shallow (quasi-)bound state exists close to the unitary limit. From the effective range expansion, the scattering parameters of the $n\Omega$ system are $1/a_0=-0.12(3)(^{+0.02}_{-0.04})$~fm$^{-1}$ and $r_{\text{eff}}=1.27(3)(^{+0.18}_{-0.00})$~fm, and those of the $p\Omega$ system, including the Coulomb interaction, are $1/a^C_0=-0.24(2)(^{+0.03}_{-0.04})$~fm$^{-1}$ and $r^C_{\text{eff}}=1.29(3)(^{+0.18}_{-0.00})$~fm. Solving the Schr\"odinger equation, we obtain the binding energy and RMS radius: $B=0.61(^{+0.40}_{-0.29})(^{+0.60}_{-0.18})$~MeV and $\sqrt{\langle r^2\rangle}=5.69(^{+1.89}_{-1.10})(^{+1.08}_{-1.46})$~fm for $n\Omega$, and $B=1.35(^{+0.46}_{-0.37})(^{+0.71}_{-0.28})$~MeV and $\sqrt{\langle r^2\rangle}=4.27(^{+0.68}_{-0.53})(^{+0.58}_{-0.72})$~fm for $p\Omega$. The joint distribution of $B$ and $\sqrt{\langle r^2\rangle}$ reveals a strong inverse correlation, providing tighter constraints on the bound-state properties.

Speaker: Liang Zhang (Institute of Modern Physics, Fudan University)

Parallel 4

61 Jet quenching and medium response via hadron chemistry around jet with the CoLBT-Hydro model

Jet-induced medium excitation and the resulting diffusion wake are essential components of jet-medium interactions in the Quark-Gluon Plasma (QGP). The modification of hadron chemistry, particularly the baryon-to-meson and strange-to-non-strange yield ratios, provides a unique probe of such medium excitations, as recently hinted at by experimental observations.
In this work, we present a comprehensive study of the chemical composition in both the near-side and away-side jet regions. We calculate the baryon-to-meson ($p/\pi$) and strange-to-non-strange ($K/\pi$) ratios correlated with quenched jets in Pb+Pb collisions at $\sqrt{s_{NN}} = 5.02~\mathrm{TeV}$.
Our results for the near-side hadron chemistry show good agreement with the experimental data. We further examine the $p/\pi$ and $K/\pi$ ratios on the away side in dijet events. We have also extended our study to $\gamma$-jet events.

Speaker: Cong Yi (CCNU)

62 Jet-induced medium response and production of thermal recoil jets in relativistic heavy-ion collisions

In the established paradigm of jet quenching in relativistic heavy-ion collisions, jets from initial hard parton scatterings are suppressed due to their interaction with the quark-gluon plasma (QGP), serving as crucial tomographic probes of QGP properties. Within the linear Boltzmann transport model, we find that the QGP is also capable of absorbing and reprocessing energy deposited by the hard jets into emergent jet-like objects, providing an alternative production mechanism of thermal recoil jets. These emergent thermal recoil jets exhibit distinct transverse momentum ($p_T$) and jet cone size ($R$) dependencies different from the hard jets, and explain the puzzling RHIC and LHC observations of the enhanced yields of hadron- and photon-triggered jets at large azimuthal angle relative to the away side but solely for jets with low $p_T$ and large $R$. Markedly different behavior is predicted for hadron-triggered heavy-flavor jets, since the hard production of heavy quarks suppresses the thermal production of jets. The thermal recoil jets are predicted to have unique substructures, such as a jet shape that increases with radius, a thermal-like distribution of their constituents, and a large-angle enhancement in their energy-energy correlators, which await verification in future experimental analyses.

Reference: Peng Jing, Yichao Dang, Lejing Zhang, Yang He, Shanshan Cao, Li Yi, Xin-Nian Wang, arXiv:2512.12715, accepted by Phys. Rev. Lett.

Speaker: Lejing Zhang (Shandong University)

63 Exploring Transverse Spin Correlations and Gluon Linear Polarization

Spin correlations of back-to-back dihadrons can emerge in unpolarized high-energy collisions, offering opportunities for unpolarized experiments to access spin-dependent fragmentation functions. In particular, transverse spin correlations of a partonic $q\bar q$ pair can manifest themselves through di-hadron production, providing a novel probe of the chiral-odd fragmentation function $H_{1T}(z)$. While produced gluons can also exhibit linear polarization correlations, such effects cannot be accessed through $\Lambda\bar{\Lambda}$ pairs at leading twist. We therefore propose a different method to probe gluon linear polarization using energy correlations in hard scattering processes. By performing an all-order CCFM analysis, we exploit the characteristic $\cos 2\phi$ azimuthal modulation of energy-energy correlators (EECs) initiated by polarized gluons to extract information on their linear polarization. These predictions can be tested at current and future facilities, including the LHC, RHIC, HERA, and the EIC.
References:
[1] Lei Yang, Yu-Kun Song, Shu-Yi Wei, Phys. Rev. D 111 (2025) 054035;
[2] Yu-Kun Song, Shu-Yi Wei, Lei Yang, Jian Zhou, Phys. Rev. Lett. 136 (2026) 131901.

Speaker: Lei Yang (Shandong University)

64 A practical methodology for $\Lambda$ global polarization extraction in fixed-target experiments

Non-central heavy-ion collisions generate large orbital angular momentum in the created medium, which leads to polarization of final-state particles via spin–orbit coupling, known as global spin polarization. The observation of significant global polarization of $\Lambda$ hyperon in heavy-ion collisions indicates that the quark–gluon plasma is the most vortical fluid known in nature. Exploring $\Lambda$ global polarization at lower energies is important for understanding spin dynamics across different regions of the quantum chromodynamics (QCD) phase diagram. Low-energy nuclear experiments are typically conducted with asymmetric detector acceptance, as in fixed-target collisions at RHIC-STAR, and at facilities such as FAIR, NICA, HIAF and HIRFL-CSR. The asymmetric rapidity coverage in these experiments enhances the coupling between directed flow and detector inefficiencies, creating significant bias in $\Lambda$ global polarization measurements. In this paper, we propose a methodology to eliminate such bias arising from asymmetric detector acceptance. The method is validated using realistic detector simulations based on the STAR fixed-target configuration.

Speaker: Diyu Shen

65 Report on the Korean Contribution to the Endcap Timing Layer for the CMS MIP Timing Detector

The MIP Timing Detector (MTD) for the CMS (Compact Muon Solenoid) experiment is designed as the timing detector for the HL-LHC era to mitigate the effects of high pile-up using 4-dimensional spatial information. Precise timing information from the MTD will improve the quality of physics analysis, particularly through particle identification in the low-momentum region, especially with data from heavy-ion collisions. For the forward region, a technique based on Low Gain Avalanche Diode (LGAD) sensors paired with the Endcap Timing Read-Out Chip (ETROC) ASIC has been selected. Many Korean institutes and fabrication facilities will contribute to the manufacturing effort, focusing on the post-processing of LGAD sensors. In this presentation, the current status of the MTD project will be presented, with emphasis on the contributions of the Korean group.

Speaker: Hyunchul Kim (Chonnam National University)

Lunch (Buffet)

Parallel 1

66 From Magnetic to Inverse Magnetic Catalysis: The Interplay of Quark and Gluon Mass Generation in Magnetic Fields

We analyze the effects of the magnetic field on the quark and gluon propagators within the functional QCD framework. By solving the coupled Dyson–Schwinger equations for the quark and gluon propagators, we find that the quark mass is generally enhanced in the presence of a magnetic field, leading to magnetic catalysis of the chiral condensate. Meanwhile, the magnetic field also induces an increase in the gluon screening mass. The enhancement of the gluon screening mass suppresses the quark–gluon interaction and thereby weakens the strength of dynamical chiral symmetry breaking, establishing a competing mechanism against magnetic catalysis. In particular, this enhancement of the gluon screening mass becomes dominant near the chiral phase transition, which in turn gives rise to inverse magnetic catalysis.

Speaker: Fei Gao (BIT)

67 Collective flow and nuclear geometry in collider and fixed-target collisions at LHCb

In heavy-ion collisions, collective flow arises from the response of the produced medium to the initial-state geometry. Measurements of azimuthal particle correlations provide powerful tools to investigate the emergence of collective behaviour, the transport properties of hot QCD matter, and the role of nuclear geometry in the initial state. The LHCb experiment offers unique capabilities for such studies through its forward rapidity coverage and its dedicated fixed-target programme. This contribution presents recent LHCb measurements of collective flow in collider and fixed-target heavy-ion collisions.

Measurements of azimuthal particle correlations in PbPb and pPb collisions at forward rapidity allow the longitudinal structure of collective phenomena to be investigated in a kinematic region not covered by other LHC experiments. Comparisons between forward and backward rapidity regions in asymmetric collision systems further provide sensitivity to the mechanisms driving collectivity in small systems.

In addition, the diverse fixed-target data samples collected by the LHCb experiment enable studies of the impact of nuclear geometry on final-state particle correlations. By comparing collision systems involving targets with different nuclear structures, flow measurements can probe the connection between nuclear shape, initial-state anisotropy, and the subsequent hydrodynamic evolution of the produced medium. In particular, recent measurements in PbNe collisions provide experimental evidence for the distinctive bowling-pin geometry of ground state $^{20}$Ne nucleus, demonstrating the sensitivity of collective flow to nuclear structure in high-energy collisions.

Speaker: Zhengchen Lian (Tsinghua University (CN))

68 Exploring the fluid behavior in small systems with viscous anisotropic hydrodynamics

We investigate the applicability of hydrodynamics in small collision systems by comparing viscous anisotropic hydrodynamics (VAH) with conventional viscous hydrodynamics (VH). In $\sqrt{s}=13$ TeV p+p collisions, VAH successfully describes $v_2\{2\}$, $v_3\{2\}$, and the negative $c_2\{4\}$, whereas VH requires evolution characterized by large shear Knudsen numbers. We further compare VAH and VH in $\sqrt{s_{\mathrm{NN}}}=5.36$ TeV O+O and Ne+Ne collisions. Their predictions are generally similar, but differences emerge in $v_3\{2\}$ and $v_4\{2\}$ in peripheral collisions. These results help constrain the applicability of conventional hydrodynamics and quantify non-equilibrium effects across small collision systems.

Speaker: Yiiyang Peng (北京大学理论物理研究所)

69 Evidence of nuclear geometry-driven flow in light-ion collisions at the LHC

A central question in strong-interaction physics, governed by quantum chromodynamics (QCD), is whether femto-scale droplets of quark–gluon plasma (QGP) form in small collision systems involving projectiles significantly smaller than heavy ions. Collisions of light ions such as 16O and 20Ne offer a unique opportunity to probe the emergence of collective behavior in QCD matter. This work presents the first measurements of elliptic (v2) and triangular (v3) flow of charged particles in the OO and Ne-Ne collisions at √sNN = 5.36 TeV at the LHC. The hydrodynamic model predictions, explicitly incorporating the nuclear structures of 16O and 20Ne, exhibit a good agreement with the flow measurements presented. The observed increase of v2 in central Ne–Ne collisions relative to OO collisions, driven by the nuclear geometries, highlights the importance of utilizing light nuclei with well-defined geometric shapes to constrain the initial conditions. These findings support the presence of nuclear geometry-driven hydrodynamic flow in light-ion collisions at the LHC.

Speaker: Zhiyong Lu (China Institute of Atomic Energy (CN))

70 Probing the tetrahedral 𝛼 clusters in relativistic 16O + 16O collisions

Relativistic $^{16}$O+$^{16}$O collisions provide a valuable opportunity to study both the quark-gluon plasma formed in small systems and the intrinsic structure of $^{16}O$. Recent implementations of ab initio nuclear configurations in heavy-ion simulations have produced different predictions for cluster-sensitive observables, making it difficult to identify the origin of possible 𝛼-cluster signals. In this work, we introduce a controlled sampling scheme that varies the compactness of 𝛼-cluster-induced multi-nucleon correlations while keeping the one-body density distribution of $^{16}O$ fixed. This allows us to separate effects driven by the tetrahedral one-body density from those driven by genuine multi-nucleon correlations. We show that the normalized ratios Norm($𝑣_2\{2\}/𝑣_2\{4\}$) and Norm($𝑣_2\{2\}/𝑣_3\{2\}$), together with their initial-state eccentricity counterparts, provide complementary constraints on initial-condition model dependence and cluster compactness. Hybrid hydrodynamic simulations and comparisons with recent LHC measurements further clarify the extent to which the initial-state signals survive final-state evolution. Our results provide a framework for using relativistic light-ion collisions to constrain cluster correlations in $^{16}O$.

Speaker: Jinyu Hu (USTC)

71 Resolving Ultracentral Flow with Quantum Entanglement-Driven Initial Conditions

Ultracentral nucleus–nucleus collisions provide a uniquely stringent test of fluctuating initial conditions: although their average transverse geometry is nearly azimuthally symmetric, measurements reveal an unexpected near degeneracy of elliptic and triangular flow, whereas conventional hydrodynamic calculations generally predict (v_2{2}>v_3{2}). An independent challenge is posed by the non-Gaussian structure of ellipticity fluctuations, encoded in the fourth-order cumulant. We introduce TRENTo-Entanglement, a saturation- and entanglement-motivated framework that establishes a direct connection between the entropy initiating hydrodynamic evolution and the quantum entanglement of small-(x) degrees of freedom in the colliding nuclei. The resulting nonlinear entropy-deposition mechanism modifies not only the hierarchy but also the higher-order statistics of initial-state fluctuations. We show that TRENTo-Entanglement can simultaneously bring elliptic and triangular flow toward their observed near degeneracy and generate the intrinsic fourth-cumulant structure required by the data. These results demonstrate that quantum entanglement can leave experimentally accessible imprints on collective flow and provide a qualitatively new organizing principle for modeling the initial state of high-energy nuclear collisions.

Speaker: Chenxi Liang (Fudan university)

72 Investigating system size dependence of strange hadron production at 200 GeV at STAR

Strangeness production is a sensitive probe of quark-gluon plasma formation and of how it varies with collision-system size. In central heavy-ion collisions at both RHIC and LHC, significant $\Omega$/$\phi$ ratio enhancement with relation to peripheral collisions has been observed at intermediate transverse momentum. It is also reported by ALICE that the strange-hadron-to-pion yield ratios exhibit approximate multiplicity scaling across collision systems at LHC energies. Whether this trend extends to the top RHIC energy remains an open question. The new datasets of Au+Au, isobar (Ru+Ru and Zr+Zr), O+O and d+Au taken by the STAR detector provide an opportunity to look into different colliding systems to investigate the dependence of strange hardron production on system size at $\sqrt{s_{\text{NN}}}$ = 200 GeV. The Au+Au, d+Au, and O+O systems benefit from the extended kinematic coverage provided by the iTPC upgrade, which increased the rapidity coverage and improved particle-identification capabilities compared to previous results.

In this talk, we will present the measurements of strange hadron ($\phi$, $\Lambda$, $\overline{\Lambda}$, $\Xi^{-}$, $\overline{\Xi}^{+}$, $\Omega^{-}$, $\overline{\Omega}^{+}$) production in Au+Au, isobar, O+O and d+Au collisions at $\sqrt{s_{\text{NN}}}$ = 200 GeV at mid-rapidity ($|y| < 0.5$), including transverse-momentum spectra, mean transverse momentum and yield ratios to pions. Additionally, the $\Omega/\phi$ ratios and the comparison between experimental data and model calculations in these colliding systems will be shown.

Speaker: Xiongxiong Xu (Tsinghua University)

Parallel 2

73 Summary of Femtoscopic Correlation Studies in CMS

Femtoscopic correlation measurements provide a unique tool to investigate the space-time structure of particle-emitting sources created in high-energy collisions. Using quantum statistical effects and final-state interactions between particles, femtoscopic analyses offer direct access to the source size, emission dynamics, and collective behavior of the produced matter on the femtometer scale. Such studies have become an essential component of heavy-ion physics, providing complementary information to observables of the quark-gluon plasma. In this presentation, I would like to give a summary of femtoscopic correlation studies from the CMS experiment, including the latest measurements in pp, pPb and PbPb collisions.

Speaker: Dong Ho Moon (Chonnam National University (KR))

74 Numerical simulations for relativistic spin hydrodynamics with physics-informed neural networks

We discuss numerical simulations of relativistic spin hydrodynamics solved by physics-informed neural networks (PINNs) [1]. We take advantage of PINNs to explicitly impose the total angular momentum, i.e., the sum of orbital and spin angular momentum, accurately conserved by including the conservation law directly in the loss function as a training target. This enables controlled numerical studies of the spin-orbit conversion driven by the rotational viscous effect. We study both orbital-to-spin and spin-to-orbital conversion, analogous to the Barnett and Einstein–de Haas effects, respectively. Our results provide a numerical demonstration of spin–orbit conversion in fully nonlinear relativistic spin hydrodynamics.

[1] Hidefumi Matsuda, Koichi Hattori, Koichi Murase, arXiv: 2512.17971

Speaker: Koichi Hattori (Zhejiang University)

75 Probing the system-size dependence of radial flow fluctuations in Au+Au and O+O collisions at RHIC

The expansion dynamics and transport properties of the quark-gluon plasma (QGP) are essential for understanding the evolution of matter created in relativistic heavy-ion collisions [1–5]. In particular, comparisons between different collision systems provide a powerful way to isolate the system-size dependence of collective expansion and its fluctuations, thereby improving sensitivity to the transport properties of the medium. We present STAR measurements of the $p_{\rm T}$-differential radial-flow fluctuation observable $v_0(p_{\rm T})$, which quantifies long-range correlations between particle-yield fluctuations in a given $p_{\rm T}$ interval and mean-$p_{\rm T}$ fluctuations, in Au+Au and O+O collisions at $\sqrt{s_{NN}}=200$ GeV, with Au+Au serving as the large-system reference. Using a two-particle correlation method with separated pseudorapidity subevents, we measure inclusive charged particles over $0.2 < p_{\rm T} < 10.0~\mathrm{GeV}/c$, identified pions and kaons over $0.2 < p_{\rm T} < 2.0~\mathrm{GeV}/c$, and protons over $0.5 < p_{\rm T} < 3.0~\mathrm{GeV}/c$. Both systems show a characteristic sign change and rise in $v_0(p_{\rm T})$. Identified-particle results exhibit mass ordering at low $p_{\rm T}$. The normalized differential response $v_0(p_{\rm T})/v_0$, where $v_0$ denotes the $p_{\rm T}$-integrated fluctuation magnitude, provides a way to investigate centrality dependence at low-to-intermediate $p_{\rm T}$, while its extension to high $p_{\rm T}$ provides sensitivity to possible jet-quenching contributions. A comparison of O+O and Au+Au collisions at similar multiplicity provides sensitivity to the system-size dependence of radial-flow fluctuations. Model variations indicate strong sensitivity to bulk viscosity, especially for light hadrons, while weak sensitivity to shear viscosity. These results demonstrate the potential of $v_0(p_{\rm T})$ as a differential probe of radial flow fluctuations, providing constraints on the system-size dependence of radial-flow fluctuations and on the properties of the QGP medium.

References

[1] B. Schenke, C. Shen, and D. Teaney, “Transverse momentum fluctuations and their correlation with elliptic flow in nuclear collision,” Phys. Rev. C 102, 034905 (2020). DOI: 10.1103/PhysRevC.102.034905. arXiv: 2004.00690 [nucl-th].

[2] J. Jia, “Sources of radial-flow fluctuations in the quark-gluon plasma,” Phys. Rev. Lett. 136, 112301 (2026). DOI: 10.1103/d6mc-sq8m. arXiv: 2507.14399 [nucl-th].

[3] T. Parida, R. Samanta, and J.-Y. Ollitrault, “Probing collectivity in heavy-ion collisions with fluctuations of the $p_T$ spectrum,” Phys. Lett. B 857, 138985 (2024). DOI: 10.1016/j.physletb.2024.138985. arXiv: 2407.17313 [hep-ph].

[4] ALICE Collaboration, “Long-range transverse-momentum correlations and radial flow in Pb--Pb collisions at the LHC,” Phys. Rev. Lett. 136, 032302 (2026). DOI: 10.1103/l36g-6f46. arXiv: 2504.04796 [nucl-ex].

[5] ATLAS Collaboration, “Evidence for the collective nature of radial flow in Pb+Pb collisions with the ATLAS detector,” Phys. Rev. Lett. 136, 032301 (2026). DOI: 10.1103/ldcn-r2lq. arXiv: 2503.24125 [nucl-ex].

Speaker: Yiming Xu (fudan university)

v0pT_abstract_ATHIC2026_v3.pdf

76 High-order mean transverse momentum fluctuations in Au+Au collisions at STAR

Event-by-event mean transverse momentum ($p_{\rm T}$) fluctuations provide insight into the initial-state geometry fluctuations, the thermodynamic properties, and the collective evolution of hot and dense QCD matter. In this talk, we will present STAR measurements of event-by-event mean $p_{\rm T}$ fluctuations in Au+Au collisions from the Beam Energy Scan programs, covering collider-mode as well as fixed-target data down to $\sqrt{s_{NN}}=3.0$ GeV. The analysis focuses on the centrality and collision-energy dependence of transverse-momentum correlations and higher moments of the event-by-event mean-$p_{\rm T}$ distribution, including variance, skewness, and kurtosis. The centrality dependence of the multi-particle $p_{\rm T}$ correlations is compared with the expected independent-source scaling behavior, and approximately follows a power-law dependence on the number of participating nucleons. The collision-energy dependence is studied over $\sqrt{s_{NN}}=$3.2--54.4 GeV, and exhibits a non-monotonic behavior, with the most pronounced variation observed in central collisions in the intermediate-energy region. These results are discussed in connection with temperature fluctuations, the QCD equation of state, and possible critical dynamics, with comparisons to LEFT-fRG [1], PNJL [2], and AMPT model calculations [3]. The measurements provide valuable constraints on critical fluctuations and the thermodynamic properties of strongly interacting QCD matter at high baryon density.

References

[1] J. Chen, W.-j. Fu, S. Yin, and C. Zhang, High-Order Fluctuations of Temperature in Hot QCD Matter, Physical Review D 114,014064 (2026).

[2] H. Liu, P. Wu, H.-M. Liu, and P.-C. Chu, Temperature Fluctuations in a Realistic Polyakov-Loop Extended Nambu--Jona-Lasinio Model along the Freeze-Out Line, arXiv:2607.19275 [nucl-th] (2026).

[3] Zhang, Liuyao and Chen, Jinhui and Zhang, Chunjian, Energy dependence of transverse momentum fluctuations in $\mathrm{Au}+\mathrm{Au}$ collisions from a multiphase transport model, Phys. Rev. C 111,024911 (2025).

Speaker: Yining Gao (Fudan University)

yining_abstract_v2.pdf

77 Non-monotonicity of transverse momentum correlations in Au + Au collisions at RHIC

We report the first measurements of two-particle transverse-momentum correlations (variance) for midrapidity charged particles in fixed-target Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=3.0$--$7.7$ GeV using data collected by STAR during the Beam Energy Scan Phase II program [1]. Combined with previous BES-I measurements at $\sqrt{s_{\mathrm{NN}}}=7.7$--$200$ GeV [2], the relative dynamical correlator approximately follows the $1/\sqrt{N_{\mathrm{part}}}$ scaling expected from independent particle-emitting sources at most energies. The scaling breaks down at the lowest collision energy, while additional deviations emerge in central collisions. For 0--5% central collisions, the combined data exhibit a non-monotonic beam-energy dependence with a significance of approximately $5\sigma$ relative to a monotonic baseline. In comparison, the mid-central data and AMPT calculations yield deviations of only approximately $2\sigma$ and $1.4\sigma$, respectively. Possible connections to temperature fluctuations and QCD critical dynamics are discussed using recent $2+1$-flavor LEFT-fRG and PNJL model calculations [3, 4]. The observations provide valuable input to understand the critical fluctuations and new constraints on the equation of state at high baryon density.

References

1. STAR Collaboration, "Non-Monotonicity of Transverse Momentum Correlations in Au+Au Collisions at RHIC," arXiv:2604.06434 [nucl-ex] (2026), accepted for publication in Physical Review Letters.
2. STAR Collaboration, "Collision Energy Dependence of $p_{\mathrm{T}}$ Correlations in Au+Au Collisions at RHIC," Phys. Rev. C 99, 044918 (2019).
3. J. Chen, W.-j. Fu, S. Yin, and C. Zhang, "High-Order Fluctuations of Temperature in Hot QCD Matter," arXiv:2504.06886 [hep-ph] (2025), Phys. Rev. D, 114, 014064 (2026).
4. H. Liu, P. Wu, H.-M. Liu, and P.-C. Chu, "Temperature Fluctuations in a Realistic Polyakov-Loop Extended Nambu--Jona-Lasinio Model along the Freeze-Out Line," arXiv:2607.19275 [nucl-th] (2026).

Speaker: Zheng Liu (Fudan University, Institute of Modern Physics)

ATHIC_Meeting_c2.pdf

78 Measurement of (Net-)Proton Number Fluctuations in Au+Au Collisions from RHIC-STAR : A Centrality-independent Method

Fluctuations of conserved quantities are proposed as sensitive observables to search for the QCD critical point in heavy-ion collisions. Recently, the STAR experiment has conducted precision measurement of net-proton fluctuations in Au+Au collisions at √sNN = 7.7 – 27 GeV, during the RHIC Beam Energy Scan II program [1] and reported the preliminary results of proton number fluctuation in fixed-target Au+Au collisions at √sNN = 3 – 3.9 GeV in the QM2025 conference. However, at lower collision energies, initial volume fluctuations (IVF) can significantly distort the observed event-by-event fluctuations, potentially obscures genuine energy dependence in the high order cumulant ratios. To address this issue, we have developed a novel centrality-independent analysis framework [2] that systematically suppresses the IVF background, thereby isolating the intrinsic, physics-driven fluctuations. In this talk, we present a new method that can effectively suppress the IVF effect and might provide essential insights into the possible existence of the QCD critical point and the nature of the QCD phase transition.

[1] B. E. Aboona et al. (STAR), Precision Measurement of Net-Proton-Number Fluctuations in Au+Au Collisions at RHIC, Phys. Rev. Lett. 135, 142301 (2025), arXiv:2504.00817 [nucl-ex].

[2] Z. Wang and X. Luo, A centrality-independent framework for revealing genuine higher-order cumulants in heavy-ion collisions, Physics Letters B 871, 139984 (2025), arXiv:2505.03666

Speaker: Zhaohui Wang (Central China Normal University)

79 Global polarization of $\Lambda$, $\Xi^{-}$, and $\Omega^{-}$ hyperons in Au+Au collisions at RHIC BES-II energies

We investigate the global spin polarization of $\Lambda$ hyperons and the multi-strange hyperons $\Xi^{-}$ and $\Omega^{-}$ in Au+Au collisions across the RHIC Beam Energy Scan II (BES-II) energy range, $\sqrt{s_{NN}}=7.7$--$27$ GeV. The polarization is computed using the modified Cooper--Frye formula, which includes contributions from thermal vorticity, the thermal shear tensor, and the gradient of the baryon chemical potential, combined with the (3+1)-dimensional viscous hydrodynamic framework CLVisc with SMASH initial conditions. We present the global polarization as a function of collision energy, centrality, transverse momentum, and rapidity. We find that the global polarization of $\Omega^{-}$ is systematically larger than those of $\Lambda$ and $\Xi^{-}$ because of its larger spin quantum number, but it remains below the central value of the recent STAR measurement. This discrepancy may suggest that additional mechanisms, such as spin correlations among strange quarks inside the $\Omega^{-}$, could contribute to the observed $\Omega^{-}$ polarization. We also find that the global-polarization splitting between hyperons and anti-hyperons increases toward lower collision energies and is dominated by the chemical-potential-gradient contribution.

Speaker: Gen-Hui Li (University of Science and Technology of China)

Polarization_BES_Xi.pdf

Parallel 3

80 HHaS project at HIAF

For the high-energy terminal of High Intensity heavy-ion Accelerator Facility (HIAF), we have proposed an experimental project using Huizhou Hadron Spectrometer (HHaS) [1]. It covers a wide range of physics subjects, containing the studies of light hadrons, hypernuclei, and the nuclear matter phase diagram, as well as the search for the phenomena beyond the standard model. The concept of HHaS with its expected performace and several topics of the physics aims with feasibility study results will be discussed in the presentation.

[1] X. Chen et al., "Huizhou Hadron Spectrometer -- a Proposed High-rate Experimental Setup at the High Intensity Heavy-ion Accelerator Facility", Nucl. Sci. Tech. 37 (2026) 156. https://doi.org/10.1007/s41365-026-01996-1

Speaker: Norihito Muramatsu (Institute of Modern Physics, Chinese Academy of Sciences)

81 Status of the CEE experiment at HIRFL-CSR

Heavy-ion collisions (HICs) is a unique tool for studying properties of hot and condensed nuclear matter. HICs at HIRFL-CSR energies can create nuclear matter with baryon density as high as 2 to 3 times of the saturation density. The CSR External-target Experiment (CEE) at HIRFL facility is a larger acceptance spectrometer to study QCD phase structure, Equation of State (EoS) and sub-threshold strangeness production at high baryon density region. In this presentation, the status of the CEE detector system and physics program will be discussed

Speaker: Prof. Yapeng Zhang (Institute of Modern Physics, Chinese Academy of Sciences)

82 Collision Energy Dependence of Hypertriton Production in Au+Au Collisions at RHIC

Hypernuclei are nuclear bound states composed of nucleons and one or more hyperons. Precise measurements of hypernuclei properties and production yields in heavy-ion collisions provide important insights into the hyperon–nucleon interaction and hypernuclear production mechanisms. The second phase of the Beam Energy Scan program at RHIC (BES-II) provides a unique opportunity to investigate the collision energy dependence of hypernuclei production in a wide range of baryon chemical potentials.
In this talk, we will report systematic measurements of the transverse momentum spectra and transverse momentum-integrated yields of hypertriton (${}^{3}_{\Lambda}$H) at mid-rapidity ($|y|<0.5$) in Au+Au collisions at 11 collision energies from 3.2 to 27 GeV. The energy dependence of the ${}^{3}_{\Lambda}$H yields, the ${}^{3}_{\Lambda}$H/$\Lambda$ yield ratio, and the double ratio $({}^{3}_{\Lambda}{\rm H}/\Lambda)/(t/p)$ will be presented. The results will be compared with calculations from thermal models, transport models with coalescence afterburners, and transport models with dynamical cluster formation. The physics implications for hypernuclei properties and production mechanisms in heavy ion collisions will be discussed.

Speaker: Yuanjing Ji (University of Chinese Academy of Sciences)

H3L_BESII_atheic20260804.pdf

83 Measurement of $K^{*0}$ and $K^{*\pm}$ in Au+Au Collisions at RHIC BES-II

Isospin symmetry, one of the fundamental symmetries underlying the strong interaction, predicts similar production rates of charged and neutral kaons in high-energy collisions. However, recent measurements by the NA61/SHINE Collaboration indicate an excess production of charged over neutral kaons, suggesting significant isospin symmetry breaking that challenges the expectation, and the underlying origin of this effect remains unresolved [1]. Such deviations could arise from Landau-level splitting under intense magnetic fields, which can lift the degeneracy between hadrons containing up and down quarks [2]. The study of neutral and charged vector mesons in heavy-ion collisions may serve as a probe of possible isospin-symmetry-breaking mechanisms triggered by strong magnetic fields in QCD matter. A notable example is the $K^{*0} (d\bar s)$ and $K^{*\pm} (u \bar s)$ pair, which share the same isospin but have quarks with magnetic moments differing by nearly a factor of five.

In this presentation, we present precise measurements of the transverse momentum ($p_{T}$) spectra, $p_{T}$ -integrated yields ($dN/dy$), and average transverse momentum ($\langle p_{T} \rangle$) of $K^{*0}$ and $K^{*\pm}$ at mid-rapidity in Au+Au collisions at $\sqrt{s_{NN}}$= 7.7 - 27 GeV, using data from the STAR Beam Energy Scan II (BES-II) program at RHIC. Centrality- and $p_{T}$-dependent yield ratios, such as $K^{*\pm}/K^{*0}$ and $K^{*}/K^{\pm}$, will be used to assess medium effects and possible isospin-violating trends.

References

[1] The NA61/SHINE Collaboration. Giacosa, F., Gorenstein, M. et al., “Evidence of isospin-symmetry violation in high-energy collisions of atomic nuclei”, Nat Commun 16, 2849 (2025).

[2] K. Xu et al., “Extracting the magnitude of magnetic field at freeze-out in heavy-ion collisions”, Phys. Lett. B 809, 135706 (2020).

Speaker: Pranjal Barik (Indian Institute of Science Education and Research, Berhampur)

ATHIC_abstract_pranjal.pdf

84 Probing Three-Body Baryonic Interactions via Femtoscopy Approach at STAR

The study of multi-baryon interactions, particularly those involving strange quarks, is key to understanding dense nuclear matter and the equation of state of neutron stars. While two-body nucleon-nucleon ($N$-$N$) and hyperon-nucleon ($Y$-$N$) forces are relatively well constrained, genuine three-body interactions remain largely unexplored. By comparing systems composed solely of nucleons with those containing both nucleons and hyperons, one can investigate how strangeness influences baryonic dynamics.

Femtoscopy offers a unique tool to access these few-body dynamics at distances of a few femtometers. By measuring momentum correlations among particles emitted close in space and time, femtoscopy directly probes final-state interactions and quantum statistical effects. At STAR, this technique can be applied to Au+Au collisions at $\sqrt{s_{NN}}$ = 3 GeV, where high baryon density and near-threshold particle production enable unprecedented studies of multi-baryon correlations.

In this talk, we will present the first measurements of three-baryon correlation functions for p–p–p and p–p–$\Lambda$ systems at $\sqrt{s_{NN}}$ = 3 GeV in the STAR experiment. The p–p–p correlations serve as a baseline for $N$-$N$-$N$ dynamics, while the inclusion of $\Lambda$ hyperons in the p–p–$\Lambda$ systems allows us to explore how strangeness modifies three-body forces through $Y$-$N$-$N$ couplings in addition to Coulomb interactions. Comparisons with theoretical calculations and transport models highlight the sensitivity of these measurements to genuine three-body forces in dense baryonic matter.

Speaker: Ms Ke Mi (University of Chinese Academy of Sciences)

85 Spin Femtoscopy: A Framework for Revealing Genuine Spin Correlations

Spin correlations are among the fundamental quantum observables in many-body systems, yet direct measurements of two-particle spin correlations in relativistic heavy-ion collisions remain challenging. Existing spin studies have mainly focused on single-particle phenomena, such as hyperon polarization and vector-meson spin alignment, while genuine two-particle spin correlations in the produced hadronic system remain largely unexplored.

In this talk, we introduce a new approach, Spin Femtoscopy, which combines spin information with femtoscopic correlation measurements to probe two-particle spin correlations. The basic idea is that different two-particle spin states can lead to distinct femtoscopic correlation functions through quantum statistical effects and spin-dependent final-state interactions. Using ΛΛ pairs as a case study, the self-analyzing weak decay of Λ hyperons enables the construction of spin-sensitive correlation functions with different singlet and triplet contributions.

We will demonstrate how this approach can be used to extract the spin-state populations of ΛΛ pairs from their correlation functions and further distinguish genuine spin correlations from spin-dependent effects arising from quantum statistics and final-state interactions. This study provides a new experimental avenue for exploring the quantum spin structure of strongly interacting matter using femtoscopy.

Speaker: Xuan Wang (Central China Normal University)

86 Investigation of $T_{cs0}^{*}(2870)^{0}$ in $pp$ collisions at $\sqrt{s}$ = 7 TeV with the PACIAE model

We have used the parton and hadron cascade model PACIAE together with the Dynamically Constrained Phase-space Coalescence model (DCPC) to study the $T_{cs0}^{*}(2870)^{0}$ production in $pp$ collision at $\sqrt{s}$ = 7 TeV, following the LHCb observation of $T_{cs0}^{*}(2870)^{0}$ in the $B^{-}\to D^{-}D^{0}K^{0}_{S}$ decays in $pp$ collisions at $\sqrt{s}$ = 7, 8, and 13 TeV [PRL 134(2025)101901]. The final hadronic states of the $pp$ collisions at $\sqrt{s}$ = 7 TeV are first simulated by the PACIAE model. Four sets of $T_{cs0}^{*}(2870)^{0}$ candidates are then recombined by the DCPC model using the constituent meson pair of $D^{0}K^{0}_{S}$, $D^{+}K^{-}$, $D^{*+}K^{*-}$, and $D^{*0} \bar{K}^{*0}$ based on the above simulated final hadronic states, respectively. We calculate their rapidity distributions, transverse momentum spectra, and angular distribution between the two component mesons, as well as angular distribution between $D$ component meson and $T_{cs0}^{*}(2870)^{0}$. Our results show that the yields of four $T_{cs0}^{*}(2870)^{0}$ candidates follow the magnitude order of $D^{0}K^{0}_{S}$ $>$ $D^{+}K^{-}$ $>$ $D^{*+}K^{*-}$ $\sim$ $D^{*0} \bar{K}^{*0}$. Similar ordering behavior is also observed in the aforementioned distributions.

Speaker: Qiang Wang (Central China Normal University)

Parallel 4

87 Low-pT ω and φ signals at forward rapidity with improved dimuon mass resolution in pp collisions with ALICE

In ultrarelativistic heavy-ion collisions, a state of deconfined quarks and gluons, the quark-gluon plasma (QGP), is created. As the system cools, it evolves into a hot and dense hadronic medium. Precise measurements of the spectral functions of low-mass vector mesons (ρ, ω, φ ) in the dilepton channel can provide information on possible restoration of chiral symmetry. As part of the ALICE upgrades for the LHC Run 3 period, a new silicon pixel detector, the Muon Forward Tracker (MFT) has been installed covering the forward pseudorapidity region 2.5 < η < 3.6. The inclusion of the MFT in the muon track reconstruction leads to an improvement in mass resolution compared to Run 2, and is expected to allow for effective heavy-flavor background separation, enabling the measurement of ω and φ dimuon invariant mass distributions. In this presentation, we report on the analysis of ω and φ mesons in the dimuon decay channel at forward rapidity in pp collisions at √s = 13.6 TeV. In particular, we demonstrate that the inclusion of MFT information in the muon-track reconstruction improves the mass resolution of the ω and φ mesons, particularly at low pT. We also present the signal-to-background ratio as a function of the dimuon invariant mass obtained with the MFT and the statistical significance of the ω and φ yield as a function of pT. These studies represent a step toward future measurements of the ω and φ meson production cross sections, which will provide an essential vacuum baseline for investigating possible in-medium modifications in Pb-Pb collisions.

Speaker: Masahiro Oida (Hiroshima University)

oida_abst_ATHIC2026_v3.pdf

88 A Novel Statistical Approach To Measure Prompt Photon Production in pp collisions at $\sqrt{s}$ = 200 GeV and 5.02 TeV

Prompt photons refer to photons produced at the level of partonic scatterings, both directly in the initial 2->2 interaction (\textit{direct}) prompt photons), or from the fragmentation of partons through next-to-leading order (NLO) interactions (\textit{fragmentation} prompt photons). However, the majority of photons produced in hadronic collisions originate from the decays of neutral mesons (decay photons), primarily from neutral pions, and constitute a large background for prompt photon studies. To suppress this background, many high transverse-momentum measurements of direct prompt photons utilize isolation criteria to suppress fragmentation and decay photons. However, such isolation criteria are challenging to describe in pQCD calculations, and the effective background suppression has limited phase space. Other measurements of prompt photons utilize a statistical decay-photon correction based on knowledge of the $\pi^0$ spectrum, which is likewise effective over only a limited phase space.

This phenomenlogical study presents a novel, data-driven statistical approach, to measure prompt photons in hadronic collisions, using the distribution of associated hadronic isolation energy (defined as the $p_\mathrm{T,iso}$ for all particles within a cone of R=0.4.) of photon candidates, which mitigates such limitations. The prompt photon population is identified by utilizing the difference in shape of the $p_\mathrm{T,iso}$ distribution for prompt and decay photons, and constructing a data-driven surrogate $p_\mathrm{T,iso}$ distribution for decay photons. We present an application of this approach to two different, pQCD-inspired general-purpose Monte Carlo models — PYTHIA 8.3 and Herwig 7.2 — demonstrating its robustness across different phenomenologies.

Speaker: Adrian Nassirpour (Sejong University)

89 Direct Photon Yield and Thermal Dielectron Flow in Isobar Collisions at STAR

Thermal dileptons, produced throughout the entire evolution of relativistic heavy-ion collisions, are unique penetrating probes of the hot and dense medium as they escape without being subject to strong interactions. By measuring the transverse momentum distribution of direct virtual photons and elliptic flow ($v_2$) of dileptons emitted from the hot QCD medium, one can extract key properties of the Quark-Gluon Plasma (QGP), such as its temperature and collective expansion, while gaining insights into the mechanisms of thermal radiation.

In this talk, we will present the first measurement by STAR of thermal dielectron elliptic flow in isobar collisions (Ru+Ru and Zr+Zr) at $\sqrt{s_{\text{NN}}}$ = 200 GeV. The thermal dielectron $v_2$ will be presented as a function of mass in different $p_T$ intervals. Additionally, we extract the direct photon invariant yield via internal conversion method. Physics implications of direct virtual photon yield and the thermal dielectron $v_2$ will be discussed.

Speaker: Xianwen Bao (Shandong University)

ATHIC2026_Abstract_ThermalDielectronv2_ver2.pdf

90 Evaluation of the neutron skin thickness via forward photon production in high-energy Pb+p collisions

The neutron skin, in which the neutron distribution extends farther out than the proton distribution in neutron-rich nuclei, is characterized by the radius $R$ and the diffuseness $a$ of each distribution, and is closely connected to the nuclear equation of state. At present, parity-violating electron scattering is essentially the only direct measurement of this quantity. We investigate a method using forward direct photons produced in high-energy lead+proton (Pb+p) collisions. By selecting the most peripheral events, in which the incident proton collides with a single nucleon of the Pb nucleus ($N_{\rm coll}=1$), the neutron skin makes the struck nucleon more likely to be a neutron. Direct photons are dominantly produced by QCD Compton scattering ($qg \to q\gamma$), for which the difference of the quark charges makes the cross section larger for a proton target than for a neutron target. Since the kinematics is governed by the high-$x$ valence quarks of the nucleon in the lead involved in the collision, this proton/neutron discrimination improves toward the direction of motion of the lead, i.e., the forward direction. Combining this geometrical effect with the isospin dependence of the hard scattering, we expect the forward photon yield ratio to be sensitive to the neutron skin thickness. Based on nucleon configurations generated with a Monte Carlo Glauber model, we determined, event by event, the species of the struck nucleon in the lead for each peripheral event, and generated direct photons in proton-proton and proton-neutron scattering with PYTHIA8, predicting the dependence of $R_\gamma(p_T) = \sigma_{\rm Pb+p}/\sigma_{pp}$ on the neutron skin thickness. In this talk, in view of future measurements with the ALICE forward calorimeter FoCal, we show that $R_\gamma$ decreases with increasing neutron skin thickness, and discuss its statistical discriminating power.

Speaker: Shou Nakajima (Sophia University)

91 Direct photon anisotropic flow as a probe of alpha clustered structure in 7A TeV 16O+16O collisions at the LHC

The anisotropic flow of direct photons is a sensitive probe of the initial geometry in relativistic heavy-ion collisions. Alpha clustering in light nuclei can enhance the initial spatial anisotropies, which can result in larger direct-photon anisotropic flow. In this work, we studied the production and anisotropic flow of direct photons for both central and peripheral collisions of $\alpha$-clustered oxygen nuclei at $\sqrt s_{NN}=7A$ TeV at the LHC, using the GLISSANDO initial-state model together with the MUSIC event-by-event hydrodynamical framework. The tetrahedral $\alpha$-clustered structure of $^{16}O$ produces a significantly larger initial triangular eccentricity compared with collisions involving nuclei with uniform-density distributions. As a result, especially in the most central events, a larger photon triangular-flow coefficient, $v_3(p_T)$, is observed compared with that obtained from collisions with uniform-density distributions. An experimental determination of photon anisotropic flow, together with the ratios of flow coefficients in O+O collisions, is therefore expected to provide valuable insight into the possible clustered structure of light nuclei and to constrain parameters in theoretical modeling.

Speaker: Pingal Dasgupta (Institut de Física d'Altes Energies (IFAE) Barcelona, Spain)

92 Deep learning approach for predicting multiple observables in Au+Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

We present a data-driven deep learning framework for predicting multiple bulk observables in Au+Au collisions at RHIC energies. A single neural network is trained exclusively on experimental measurements of charged particle pseudorapidity density distributions, transverse momentum spectra and elliptic flow coefficients over a broad range of collision energies and centralities, without using simulation outputs as training targets. The network architecture is inspired by the stages of a heavy-ion collision, from the quark-gluon plasma to chemical and kinetic freeze-out, and employs locally connected hidden layers and a structured input design that encodes basic geometric and kinematic features of the system. We demonstrate that these physics-motivated choices significantly improve test performance compared to purely fully connected baselines. The trained model is then used to predict the above observables at RHIC energies, and the results are further cross-checked against the energy dependence of the total charged particle multiplicity per participant pair, as well as against a CLVisc hydrodynamic calculation with T\raisebox{-0.5ex}{R}ENTo initial conditions. Our findings indicate that such physics-guided neural networks can provide useful data-driven interpolation tools for RHIC observables in regions not currently covered by the available measurements, and can support further phenomenological studies.

Speaker: Junqi Tao (华中师范大学)

93 Kinetic theory of spin 1/2 particles within Constrained Hamiltonian formalism

We construct a relativistic kinetic theory for spin-1/2 particle with zero magnetic moment within constrained Hamiltonian formalism. By imposing constraints on an enlarged canonical phase space, the chiral kinetic theory can be consistently reconstructed within this framework. For massive spin-1/2 particles, we introduce a two-dimensional spin phase space, leading to an eight-dimensional phase-space distribution function. The corresponding kinetic equation, together with the generalized Liouville theorem in non-trivial phase space are also derived. In the presence of electromagnetic field, the conversion among orbital angular momentum, spin angular momentum and angular momentum carried by electromagnetic field emerge naturally within this formalism. At global equilibrium, all conditions previously obtained in Winger formalism are reproduced.
By using the same framework to spinning particle with arbitrary magnetic moment, a consistent collisionless kinetic theory can be constructed. Compared with Winger formalism, there exist no approximation in this classical construction. The related classical spin phase space are also discussed in the Hamiltonian formalism. At global equilibrium, the spin potential has a elegant relation with thermal vorticity and background field in zero magnetic moment case.

Speaker: Jie Zhou

Coffee Break

Parallel 1

94 Three-dimensional imaging of the QGP with nuclear shape

The longitudinal structure of the quark–gluon plasma (QGP) is the missing third dimension in our picture of its initial state. It records how energy is deposited along the beam, how quantum fluctuations in the colliding nuclei shape the plasma, and how collective expansion converts this geometry into final-state momentum correlations. Accessing it is notoriously difficult: short-range nonflow correlations from jets and resonance decays obscure the long-range flow signal, while conventional factorization ratios provide only an indirect view. We introduce a strategy that turns nuclear shape into a controlled instrument. Subtracting correlations from similarly sized nuclei with different deformations cancels the common nonflow and fluctuation-driven baseline, isolating the deformation-driven signal. In transport simulations, deformation strongly changes the elliptic-flow amplitude while nearly preserving its normalized longitudinal profile, allowing this signal to recover the full two-rapidity correlation map. The map reveals a nonlinear, nonadditive loss of correlation and a previously unquantified, acceptance-dependent bias in standard flow measurements. Existing U+U/Au+Au, Ru+Ru/Zr+Zr, and O+O/Ne+Ne data can test the method immediately and extend it to longitudinal fluctuations in ellipticity, triangularity, and transverse size. Known nuclear shape thereby becomes a precision instrument for three-dimensional QGP imaging.

Speaker: Prof. Jiangyong Jia (Stony Brook University)

95 Resolution-matched nuclear geometry and the nucleon-size ambiguity in relativistic heavy-ion collisions

Nuclear structure theory provides point-nucleon densities, whereas high-energy nuclear collisions probe nuclei through finite-resolution hadronic interactions. When point densities are used as nucleon-center distributions in Monte Carlo initial-state models, varying the nucleon width changes both the interaction range and the folded nuclear surface. This resolution mismatch obscures the separation between nuclear structure and collision dynamics.

In this talk, I show that geometric surface inflation accounts for most of the strong nucleon-width dependence of the hadronic cross section, $\sigma_{\rm AA}$, used in recent Bayesian analyses. Holding fixed the folded density entering the Glauber phase shift removes this ambiguity, making $\sigma_{\rm AA}$ nearly insensitive to a Gaussian nucleon width and primarily sensitive to the nuclear surface. Within a two-component model, the measured cross section corresponds to a neutron-skin interval $\Delta r_{\rm np}\in[0,0.21]$ fm for $^{208}$Pb. These results establish resolution matching as a consistency requirement for connecting point-nucleon nuclear structure with finite-resolution heavy-ion collision models.

Speaker: Haojie Xu

96 Dijet Production in Intermediate x at EIC

For dijet production in deeply inelastic scattering, photon-quark scattering is important at large x, while photon-gluon fusion becomes important toward smaller x. In the large-x regime, the energetic parton
undergoes multiple scattering and gluon radiation in a large nucleus (jet quenching), where LPM interference can be observed [Y. Y. Zhang and X. N. Wang 2022]. In the small-x regime, the virtual photon
splits into a q¯
q dipole, which scatters off the Lorentz-contracted nuclear color field; saturation effects become important. There are ongoing efforts to bridge these two regimes from both directions. From
small x to large x, next-to-eikonal (NEik) corrections to the Color Glass Condensate (CGC) framework go beyond the shock-wave limit. In particular, DIS dijet production was calculated at NEik accuracy in
[Altinoluk et al. 2023]. From large x to small x, it was shown in [Fu et al. 2025] that, by adding sub-eikonal momentum phases, CGC can match the high-twist (HT) expansion formalism for direct-photon
pA production. In this work, we calculate the nuclear modification of photon-gluon fusion, i.e., the leading-order (LO) twist-4 photon-gluon channel within the generalized high-twist approach. Combining
LO twist-4 photon-quark and photon-gluon contributions, our numerical results show that the photon-gluon channel gives the dominant nuclear modification at intermediate x.

Speaker: 媛媛 张 (西南交大)

97 Color Randomization of Quarkonium State in the Glasma

We compute the time evolution of the quarkonium density matrix in the background glasma field, the primordial state of matter in relativistic heavy-ion collisions, and show how the color of the quarkonium state is randomized. This color randomization is of particular interest because it drives the quarkonium out of its color-singlet state, leading to dissociation. The resulting suppression of the quarkonium yield would serve as a promising experimental signal of the glasma, as proposed by an earlier study [1]. We analyze the time scale and magnitude of the transition from the color-singlet state to unbound color-octet states in the glasma environment.

[1] L. Oliva, G. Parisi, V. Greco, and M. Ruggieri, Phys. Rev. D112, 014008, (2025).

Speaker: Dr Hidefumi Matsuda (Zhejiang University)

98 Forward Hadron Production in p–p, p+Pb and d+Au Collisions within the CGC-Based Monte Carlo Model

We introduce MC-CGC, a new event generator built on the saturation description of particle production in pp and p(d)+A collisions. The framework incorporates radiation, realistic soft production, beam remnant treatment, and fragmentation, and is calibrated against data across multiple systems and different collision energies. Our main predictions focus on the transverse-momentum spectra and the nuclear modification factor in the forward-rapidity regions. We find that our results agree well with both experimental data and analytic calculations within the CGC hybrid framework. By providing a robust, saturation-based initial-state baseline, this generator helps to probe the existence of the CGC. This establishes a constraint on initial-stage effects, which is essential for disentangling initial-stage (CGC-driven) contributions from final-stage (hydrodynamic-driven) contributions in small collision systems.

Speaker: Shujun Zhao (PKU)

99 Addressing the Ultra-Central Puzzle with Initial-State Nuclear Structures

Hydrodynamic models fail to describe the near-equal $v_3 / v_2$ ratio observed in ultra-central heavy-ion collisions, despite their success in other centrality classes. This
failure can not be resolved by adjusting the shear viscous coefficient, as shear viscosity suppresses higher-order anisotropic flows more strongly, leading to an underestimation of $v_3$ when $v_2$ matches experimental data. To address this issue, we explore two initial-state modifications to resolve this puzzle: (1) impose a minimum distance between nucleons to simulate the homogenization effect arising from short-range nucleon-nucleon repulsion; and (2) introduce sub-nucleonic structures, specifically 'hot spots' within protons, to provide a more refined description of initial-state fluctuations. Using TRENTo initial conditions and 3+1D viscous hydrodynamic model CLVisc, both approaches significantly lower geometric eccentricity, reduce required viscosity, and narrow the $v_2$–$v_3$ gap in ultra-central collisions. Our results implicate initial-state nuclear and sub-nucleon structures as critical factors in addressing this puzzle. Resolving it would advance nuclear structure studies and improve precision in extracting QGP transport coefficients (e.g., shear viscosity), bridging microscopic nuclear features to macroscopic quark-gluon plasma properties.

Speaker: qi wang (华中师范大学)

100 Photon-Induced $J/\psi$ Azimuthal Correlations in Heavy-Ion Collisions at STAR

In relativistic heavy-ion collisions, quasireal photons are highly linearly polarized, giving rise to characteristic azimuthal correlations in vector-meson decays. In ultra-peripheral collisions, the spin-interference effect can be quantified through the azimuthal modulation between the $J/\psi$ transverse momentum and its decay-lepton axis, providing sensitivity to the transverse spatial structure of the photonuclear interaction. In non-central hadronic collisions, the photon polarization inherited by the decay leptons can be measured relative to the event plane, offering direct access to the direction of the impact parameter.

In this contribution, we present measurements of the spin-interference-induced azimuthal modulation of photon-induced $J/\psi$ mesons in Ru+Ru, Zr+Zr, and Au+Au ultra-peripheral collisions at $\sqrt{s_{NN}}=200$ GeV. We also report measurements of the azimuthal anisotropy of electrons from photon-induced $J/\psi$ decays relative to the event plane in non-central Ru+Ru and Zr+Zr collisions at the same energy. Comparisons with theoretical model calculations and their physics implications will also be discussed.

Speaker: Kaiyang WANG

101 Recent ALICE Results on Polarization and Spin Alignment in Nuclear Collisions

Polarization and spin alignment have emerged as important tools for investigating the dynamical properties of the strongly interacting matter produced in relativistic nuclear collisions. Spin-dependent observables provide access to different aspects of the collision depending on the particle species and the choice of the spin-quantization axis. Correlations with the event or reaction plane can probe the vortical structure, global angular momentum, and early electromagnetic fields of the system, while measurements in production-related reference frames constrain the spin dynamics of particle production and its possible modification in the medium. Experimentally, the spin information is inferred from the angular distributions of decay products through weak, strong, or electromagnetic decays.

This presentation gives an overview of recent polarization measurements performed with the ALICE detector at the LHC. Longitudinal polarization measurements of hyperons in different collision systems are presented as probes of the local vortical and shear structures associated with anisotropic expansion. Measurements of the global polarization of ($\Lambda$) and ($\overline{\Lambda}$) hyperons are discussed in connection with the transfer of the initial orbital angular momentum to the spin degrees of freedom of the produced medium. The overview is then extended to the charm sector through measurements of inclusive (J/$\psi$) and prompt ($D^{*+}$) spin alignment with respect to the direction perpendicular to the reaction plane in Pb–Pb collisions. These results test possible correlations between heavy-quark spin and the global collision geometry, with sensitivity to charm-quark transport, early electromagnetic fields, quarkonium evolution, and hadronization. Finally, (J/$\psi$) polarization measurements in the helicity and Collins–Soper frames in pp and Pb–Pb collisions are presented to investigate production-related polarization and its possible modification in the nuclear medium. Together, these measurements illustrate how complementary choices of particle species, collision system, and reference axis provide access to distinct aspects of spin dynamics in high-energy nuclear collisions.

Speaker: Junlee Kim (Fudan University)

102 Study of spin correlations for Λ hyperon pairs in pp collisions at √s = 13.6 TeV using LHC Run 3 data with ALICE

Hyperon spin correlations have recently attracted significant interest as a probe of QCD spin dynamics. A recent theoretical study suggests that the spin correlation for Λ hyperon pairs is a sensitive probe to separate strong-force-field-induced vector meson spin alignment from hydrodynamic effects, and to probe spin-orbit coupling, polarization transfer, and possible spin entanglement in fragmentation.
Using high-statistics ALICE data, we present the first precision measurements of spin correlations for Λ¯Λ, ΛΛ, and ¯Λ ¯Λ pairs in pp collisions at √s = 13.6 TeV, as a function of their relative separation in pseudorapidity and azimuth, and compare them with model predictions. These measurements constrain spin generation and hadronization models, distinguish fragmentation from recombination, and serve as a reference for future heavy-ion studies, where hyperon spin correlations separate hydrodynamic and strong-field contributions to spin polarization.

Speaker: Youpeng Su (Central China Normal University)

103 Interaction Geometry and Hidden Bias in Learning Lattice Spin Systems

An autoregressive neural sampler writes a lattice configuration site by site, each site conditioned on the sites already written, and it returns independent samples with an exact likelihood. Each conditional sees only a context window of fixed reach, and nothing in the architecture says how far that reach has to extend.

Set the reach one unit short of what the target needs and the interior bonds come out if anything too ordered, while the susceptibility can be statistically indistinguishable from the truth. But the susceptibility only integrates the correlation function, and its shape is wrong by an order of magnitude more.

The requirement is combinatorial. In a local model the sites already written act on the rest only through the frontier between them, and the generation order never pushes that frontier further back than its own bandwidth. We prove that a contiguous window represents the exact conditionals of every such target precisely when its reach is at least that bandwidth, the largest gap the order leaves between two coupled sites. Across more than a hundred temperature-conditioned samplers, spanning lattice sizes, boundary conditions, orders, depths and targets beyond Ising, the verdict follows the bandwidth. One unit of bandwidth is enough to flip it, and in a separate pair orders that tie on cut width still split.

The required context can therefore be computed from the interaction graph of any local target before a single training run, and on the torus a well-chosen order drops it from the number of sites to its square root. The thermodynamic observables can pass either way, so a check without ground truth has to read the shape of the correlation function.

Speaker: TAEGEUN KIM (Fudan U. / RIKEN)

Parallel 2

104 Static Quark--Antiquark Interactions in Rotating SU(3) Gluodynamics

In this talk I will present a study of static quark--antiquark interactions in rotating SU(3) gluodynamics using quenched lattice simulations at imaginary angular velocity. At zero temperature, we extract the static potential from Wilson loops for quark--antiquark pairs aligned with the rotation axis, for transverse pairs with one source on the rotation axis, and for symmetric transverse pairs across the rotation axis. Within the present accuracy, no significant rotation dependence or anisotropy is observed in the zero-temperature potential.
At finite temperature, imaginary rotation suppresses the color-averaged free energies obtained from Polyakov-loop correlators in both longitudinal and transverse geometries. Axial–diagonal comparisons are used to identify a bulk region where open-boundary artifacts are reduced. In this region, the large-distance longitudinal free-energy shift is well described by $\Delta F_z(R_{xy})=A R_{xy}^2+B$. The transverse channels exhibit the same qualitative suppression, while their distance dependence additionally reflects the radial arrangement of the static sources and is compatible with a radial single-source free-energy shift in the bulk region. For the finite-temperature observables studied above $T_c$, the response weakens as the temperature is increased.
These results provide lattice evidence for a position- and geometry-dependent response of bare static-source free energies to imaginary rotation in a gluonic medium.

Speaker: Hai-Tao Shu (CCNU)

105 Vector-Meson Spin Alignment from Anisotropic Quark or Hadron Coalescence

The distribution of particles is highly anisotropic in the initial stage of a heavy-ion collision. We demonstrate that this anisotropy induces a sizable effect on the spin alignment of vector mesons. We study two different production mechanisms for ϕ and K∗0 mesons, on one hand the coalescence of quarks and on the other that of pseudoscalar mesons. In the quark-coalescence picture where ϕ and K^{∗0} are produced via a bare vector coupling to quarks, a negative δρ{00} of order 10^−3 is observed. In contrast, when ϕ and K∗0 are produced via quark coalescence with a vertex with spin-orbit coupling, or when they are produced via pseudoscalar-meson coalescence, a positive δρ{00} emerges. In all cases, the magnitude of the spin alignment is directly proportional to the degree of anisotropy. The sign difference between the cases provides a possibility to clarify the production mechanism for vector mesons.

Speaker: Wen-Bo Dong (University of Science and Technology of China)

106 Measurements of the Correlation between Elliptic Flow and Λ Hyperon Local Polarization in Isobar Collisions with STAR at RHIC

The longitudinal local polarization $(P_{z,s2})$ of $\Lambda$ and $\bar{\Lambda}$ hyperons exhibits a second-harmonic azimuthal modulation that is closely related to the anisotropic expansion and velocity-gradient structure of the produced medium. Measurements of local polarization in 200 GeV Au + Au and isobar collisions at RHIC exhibit similar centrality dependence, increasing in more peripheral collisions. However, the results in 8.16 TeV $p$-Pb collisions at LHC indicate that the multiplicity dependence of local polarization follows a trend opposite to that of elliptic flow, raising questions about a simple direct relationship between the two observables. We employ the Event Shape Engineering method, which uses event-by-event variations of the second-order flow vector to select event classes with different elliptic-flow magnitudes within a given centrality interval, to measure $P_{z,s2}$ as a function of $v_{2}$ in Ru + Ru and Zr + Zr at $\sqrt{s_{NN}}$ = 200 GeV by the STAR experiment. In addition, we present a measurement of the covariance between event-by-event $P_{z,s2}$ and $v_{2}$. The results reveal a weak dependence of $P_{z,s2}$ on $v_{2}$. These findings will help improve our understanding of whether the second-harmonic local polarization is simply governed by the magnitude of elliptic flow, or whether a more complex underlying mechanism is responsible.

Speaker: Zhiyi Wang (Fudan University)

ATHIC2026_abstract_zhiyi.pdf

107 Event-Shape Dependence of Prompt D⁰ Meson Elliptic Flow in PbPb Collisions at 5.02 TeV with CMS

Understanding the origin of prompt D0 meson elliptic flow helps us to learn how charm quarks interact with the quark-gluon plasma (QGP), with the initial state determined by the event-by-event collision geometry. The event shape-dependent elliptic flow can be understood in detail using the event shape engineering (ESE) technique. ESE correlates light hadron elliptic flow, a proxy for the collision eccentricity, to that of the D0 mesons. In this talk, we present the prompt D0 meson ESE in PbPb collisions at $\sqrt{s_{NN}}=5.02$ TeV measured with the CMS detector. A strong linear correlation between the D0 meson and charged-particle $v_2$ is observed for low transverse momenta in the collision centrality range 10-40%. The strong correlation suggests that charm quarks are modified in the same way as light hadrons, which supports a high level of fully thermalized charm inside the QGP. The results are compared with model calculations that describe the thermalization and collective motion of D0 mesons and charged particles.

Speaker: Junseok Lee (Korea University)

108 Holographic spectral functions of exotic spin–1 mesons

We develop a general holographic framework for computing thermal spectral functions of exotic spin–$1$ mesons. A bulk Proca mass encodes the canonical ultraviolet dimension of the interpolating operator, allowing channels with different ultraviolet scaling to be treated within a unified membrane flow formalism in the zero-spatial-momentum limit. We test this framework in a soft-wall model with a gluon-condensate background for the hybrid $\pi_1$ and tetraquark-like $Z_c$ channels. The results show that dissociation temperatures of both channels lie below the phase transition temperatures. Increasing gluon condensate $c$ delays dissociation in both channels, but through different effects: both the vacuum-mass shift and thermal spectral deformation contribute in the $\pi_1$ channel, whereas the latter dominates in the $Z_c$ channel. Nevertheless, for the same environment, the $Z_c$ resonance dissociates at a lower temperature than the $\pi_1$ resonance.

Speaker: 彦清 赵 (海南师范大学)

109 Spin-dependent azimuthal asymmetry of coherent $J/\psi$ photoproduction in peripheral PbPb collisions with CMS

Linearly polarized quasireal photons from relativistic heavy ions can transfer their polarization to coherently photoproduced vector mesons, producing a second-harmonic modulation in their decay angular distributions. A positive modulation has been observed for spin-0 pions from coherent $\rho^{0}$ decays, using the $\rho^{0}$ transverse momentum direction as the polarization reference, while a negative one is predicted for spin-$\frac{1}{2}$ leptons from $J/\psi$ decays. Since the correlation between the meson transverse momentum and polarization directions induced by two-source interference weakens at forward rapidity or in asymmetric systems, and the reconstructed direction of a low-$p_{\mathrm{T}}$ coherent $J/\psi$ is sensitive to detector resolution and final-state radiation, the second-order event plane, which approximates the impact-parameter direction, provides a more robust polarization reference.

In this talk, we present the first observation of the $\cos(2\Delta\phi)$ modulation of positive muons from coherently photoproduced $J/\psi\to\mu^{+}\mu^{-}$ decays relative to the second-order event plane, including its centrality and rapidity dependence. The measurement directly tests the predicted spin-state dependence, evaluates whether decay product directions from coherently photoproduced vector mesons can provide a complementary estimate of the reaction-plane orientation, particularly in small systems affected by nonflow and geometry fluctuations, and can constrain models of coherent photonuclear production in hadronic collisions.

Speaker: Xueli Hua (South China Normal University)

110 Anisotropic chromo-field fluctuations and spin alignment of quarkonia

Spin correlation is believed to be a significant contribution to vector meson spin alignment. In this work, we study the generation of spin correlation through fluctuations of the chromomagnetic field in the quark-gluon plasma medium. We show that anisotropic fluctuations generically lead to finite spin alignment of vector mesons. We study two sources of anisotropic chromomagnetic field fluctuations: one comes from the motion of a vector meson with respect to the medium, with the boosted isotropic fluctuations in the medium turning into anisotropic ones in the vector meson's frame. The other comes from the shear flow of the QGP, with the anisotropy arising from viscous corrections to the gluon distribution function. We apply these mechanisms to study the spin alignment of J/ψ in the QGP. The chromofield correlators are evaluated using hard-thermal-loop (HTL) spectral functions. We find that the motion-induced contribution gives rise to negative spin alignment in the forward-rapidity region, while the shear-induced contribution is subleading. The mechanism is also expected to make a significant contribution to the spin alignment of ϕ.

Speaker: Yuhao Liang (Sun Yat-Sen (Zhongshan) University)

111 Unraveling the neutron skin thickness through jet charge in deep inelastic scattering

The neutron skin thickness in neutron-rich nuclei has traditionally been measured using low-energy hadronic and electronic scatterings at hadronic level. In this paper, we propose a novel probe of the neutron skin thickness through deep inelastic scattering in high-energy electron-ion collisions, leveraging the intrinsic correlation between final-state jet charge distribution and initial-state partonic distributions in nucleons.} Specifically, we demonstrate the sensitivity of jet charge distribution to the neutron skin thickness in $e$+Pb collisions with varying centralities, and in isobar collisions of $e$+Ru and $e$+Zr. We predict a strong suppression of positive jet charge distribution and an enhancement for negative jet charge distribution in peripheral electron-ion collisions, revealing the neutron skin effect. This proposal can also be extended to photon and Z-boson tagged jet charge distribution in proton-nucleus collisions at the Large Hadron Collider, providing an alternative access to neutron skin thickness.

Speaker: 善良 张 (湖北大学)

112 Collective Flow Modulated Radiation Effects on Jet Substructure in Monte Carlo Approach

Recent theoretical advances have shown that collective flow imparts a large asymmetry to both the momentum broadening distribution and the medium-induced radiation spectrum of jet partons. In this work, we present the first inclusion of the full flow-induced anisotropic radiation spectrum in a heavy ion jet Monte Carlo as a large scale overhaul of the open-source APE (Anisotropic Partonic Evolution) package. Our approach implements an efficient event-by-event calculation of the full radiation distribution in realistic, Bayesian-inference tuned hybrid transport media. Using this new tool, we study the effect of collective flow on jet substructure, focusing especially on novel vector correlations between jet substructure and the event geometry.

Speaker: Joseph Bahder (Central China Normal University)

113 Analysis of Nuclear Fragmentation Functions for Pions with $A$ and $\nu$ Dependence

We present a QCD analysis of pion nuclear fragmentation functions (nFFs), which encode nuclear modifications to hadronization in high-energy nuclear collisions. Within this framework, vacuum fragmentation functions and their nuclear modifications are extracted simultaneously. The nuclear effects are parameterized as functions of the mass number $A$, the energy of the fragmenting parton in the target rest frame $\nu$, and the hadron energy fraction $z$, allowing their dependence on these variables to be quantified. Our analysis includes semi-inclusive deep-inelastic scattering data on nuclear targets, with kinematic cuts chosen to ensure the applicability of perturbative QCD and collinear factorization. The resulting fit provides a good description of most datasets, with the nFFs well constrained in the energy fraction range $z \in [0.2,\ 0.7]$. Additionally, with our new nFFs, we present next-to-leading order predictions in $pp$ and $pA$ collisions, which show reasonable agreement with ALICE data within the current experimental uncertainties.

Speaker: 萌阳 李 (上海交通大学)

Parallel 3

114 Measurement of $\Lambda$-binding energies of light hypernuclei in Au+Au collisions at $\sqrt{s_{NN}}=3~$GeV at RHIC

Hypernuclei, which are special nuclei formed by nucleon cores and hyperons, are ideal platforms to study the hyperon-nucleon interactions. The $\Lambda$-binding energies ($B_{\Lambda}$) of hypernuclei are direct observables encoding the ΛN and ΛNN interactions, which are relevant to understanding the ``hyperon puzzle'' in neutron stars. However, the measurements on the $B_{\Lambda}$ of light hypernuclei are still controversial. A recent measurement by the A1 Collaboration reported $B_{\Lambda}$($^{3}_{\Lambda}{\rm H}$) = 523 $\pm$ 13 (stat.) $\pm$ 75 (syst.) keV, substantially larger than the historical world-average value of approximately 120 keV. For the mirror hypernuclei pair $^{4}_{\Lambda}{\rm H}$ and $^{4}_{\Lambda}{\rm He}$, the charge-symmetry breaking (CSB) manifests itself as a difference in their $B_{\Lambda}$. The CSB in the ground state and the excited state reveal the difference between the $\Lambda$-p and $\Lambda$-n interactions. Together, these considerations motivate independent high-precision measurements.

As part of the STAR fixed target program, the STAR detector collected data in Au+Au collisions at $\sqrt{s_{NN}}=3~$GeV. The high production yield of light hypernuclei provides an opportunity to measure their $B_{\Lambda}$ precisely. In this talk, we will present the measurement of the $B_{\Lambda}$ of $^{3}_{\Lambda}{\rm H}$, $^{4}_{\Lambda}{\rm H}$, and $^{4}_{\Lambda}{\rm He}$ with about 2 billion Au+Au collision events at $\sqrt{s_{NN}}=3~$GeV collected in 2021. The results will be presented together with the methods, calibrations, and systematic uncertainties of the measurements.

Speaker: 天浩 邵 (复旦大学)

ATHIC2026-abstract-hypernuclei-STAR-v2.pdf

115 Development of an Online Physics Event Identification Algorithm for Streaming Reconstruction in ePIC

The Electron-Ion Collider (EIC), which is scheduled to begin operations at Brookhaven National Laboratory in the 2030s, will explore the quark and gluon structure of nucleons and nuclei, including the emergence of gluon saturation at high densities. Through high-energy collisions of polarized electrons with protons and nuclei, the EIC will provide new insights into the structure and dynamics of strongly interacting matter. The ePIC experiment is being developed as the first detector at the EIC to realize this broad physics program. This study aims to develop algorithms and a software framework for online physics event identification for the ePIC experiment.

The ePIC experiment adopts a streaming data acquisition system based on continuous detector readout to maximize its physics reach. Detector data are aggregated into fixed-duration timeframes (0.6 ms) that contain detector responses from multiple physics interactions together with beam-induced background and detector noise.  In this approach, physics events are identified in software rather than by hardware triggers. Together with AI-based methods, this approach also enables real-time experimental monitoring and control, as well as calibration and full event reconstruction within a few weeks of data taking.

In this study, we are extending the EICrecon software framework to support streaming reconstruction. At the core of EICrecon, JANA2 provides a hierarchical data processing model that allows data to be processed at different levels, including the timeframe level and the physics-event level. EICrecon builds on this capability to process data from continuous detector readout in timeframes and to identify temporally localized physics-event candidates within each timeframe. The selected candidates are then passed to the standard event-level reconstruction chain. We evaluated the performance of the developed event-identification algorithm using simulations that incorporate beam-induced backgrounds at realistic rates. In this presentation, we will describe the streaming event-identification approach implemented in EICrecon and present its event-identification efficiency. We will also briefly discuss how this approach has been applied to recent ePIC test-beam measurements.

Speaker: Takuya Kumaoka (University of Tokyo, QNSI)

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116 Exploring Nuclear Clustering and Deformation with Transverse-Momentum Observables at CEE/HIRFL-CSR and HIAF Energies

Nuclear clustering and intrinsic deformation are important manifestations of many-body correlations in nuclei. At RHIC and the LHC, collective flow and transverse-momentum correlations have been extensively explored as probes of initial-state nuclear structure [1]. Building on recent studies of $\alpha$ clustering and U+U deformation at CSR energies [2,3], we investigate whether transverse-momentum observables provide complementary sensitivity to nuclear structure at the lower collision energies relevant to the CEE experiment at the HIRFL-CSR facility in Lanzhou and the HIAF program in Huizhou. Here, we use the Jet AA Microscopic Transport Model (JAM) at $\sqrt{s_{NN}}=2.36$~GeV. We study $^{12}$C+$^{12}$C, $^{12}$C+$^{208}$Pb, and $^{16}$O+$^{16}$O collisions with different $\alpha$-cluster configurations, and $^{238}$U+$^{238}$U collisions with different quadrupole and hexadecapole deformations. We find that, unlike at high energies, the conventional mapping between initial-state eccentricity and final-state collective flow is substantially weakened at low collision energies, limiting flow as a direct probe of nuclear geometry. In contrast, the mean transverse momentum and its event-by-event cumulants, including $c_2$ and $k_2$, as well as transverse-momentum correlations, remain sensitive to the compactness and underlying configuration of the participant system, carrying quantitative information on clustering and deformation. These results highlight transverse-momentum observables as a complementary approach to probing nuclear many-body structure and motivate their experimental study in the low-energy programs at CEE and HIAF. The fixed-target configurations provide additional flexibility to vary projectile and target nuclei, offering a systematic approach to disentangling different aspects of nuclear structure.

[1]. STAR Collaboration, Nature 635, 67 (2024), J. Jia et al., Nucl. Sci. Tech. 35, 220 (2024).
[2]. S. Singha, arXiv:2602.08288.
[3]. A. Sahoo et al., Phys. Rev. C 109, 054902 (2024).

Speaker: Subhash Singha (Institute of Modern Physics CAS)

117 ALICE 3: Outer Tracker project from the Korea ALICE group

ALICE 3 is the next-generation detector system proposed for LHC Runs 5 and 6. Its main tracking system is based on CMOS Monolithic Active Pixel Sensor (MAPS) technology, providing broad pseudorapidity coverage and consisting of an Inner Tracker (IT) and an Outer Tracker (OT). This talk focuses on the ongoing efforts on the OT project by the Korea ALICE group (KoALICE).

The OT is composed of three barrel layers and 12 forward disks, with a total active area exceeding 60 m^2. The detector is designed to provide excellent tracking performance while maintaining a low material budget, making it a key component of the ALICE 3 physics program. KoALICE contributes to multiple aspects of the OT project, including sensor post-processing, module design and production, and disk design and assembly. Recent progress in these activities, together with the current status of the detector R&D, will be presented, highlighting KoALICE's contributions to the development of the ALICE 3 Outer Tracker.

Speaker: Saehanseul Oh (Sejong University)

SOh_ATHIC2026_abstract.pdf

118 Current Status and Feasibility Studies of the MPD Experiment at NICA

The Multi-Purpose Detector (MPD) is a flagship experiment at the Nuclotron-based Ion Collider fAcility (NICA) at the Joint Institute for Nuclear Research (JINR). It is designed to investigate strongly interacting matter at high net-baryon densities through systematic measurements of heavy-ion collisions at center-of-mass energies of $\sqrt{s_{\mathrm{NN}}} = 4-11~\mathrm{GeV}$ in collider mode. Its broad physics program aims to map the high-density region of the quantum chromodynamics (QCD) phase diagram, probe the onset of deconfinement, and search for signatures of a possible QCD critical point.

This report presents the current status of the MPD experiment and selected results from feasibility studies based on simulated $\mathrm{Bi+Bi}$ collisions at $\sqrt{s_{\mathrm{NN}}} = 9.2~\mathrm{GeV}$. These results illustrate the anticipated detector performance and demonstrate MPD's capability to measure key observables sensitive to the properties and evolution of strongly interacting matter.

Speaker: Yonghong Wang (山东大学)

119 The ALICE ITS3 Upgrade: A wafer-scale cylindrical MAPS tracker

During the LHC Long Shutdown 3 (2026–2030), the ALICE collaboration will upgrade its three innermost tracking layers with the Inner Tracking System 3 (ITS3), the first fully cylindrical, wafer-scale silicon vertex detector. Built on 65 nm CMOS MAPS technology, ITS3 features silicon thinned to 50 µm and bent into self-supporting cylindrical layers at radii of 19, 25, and 32 mm. Wafer-scale stitching enables 27 cm-long seamless sensors with direct signal and power routing, eliminating flexible printed circuits over the active area and drastically reducing passive mass.

These self-supporting sensors maintain over 99% detection efficiency and a spatial resolution of approximately 5 µm. By combining this sensor technology with ultra-light carbon-foam support structures with forced-air cooling instead of traditional frames and water cooling, the total material budget drops to under 0.09% X0 per layer.

Extensive lab and test-beam campaigns have validated the ITS3 architecture, demonstrating stitching feasibility, high yield, and radiation hardness in earlier sensor prototypes. Currently, a characterisation campaign is underway for the final full-scale prototype, MOSAIX. Furthermore, full-scale engineering models have confirmed thermal and mechanical performance, showing that an 8 m/s airflow successfully meets the 40 mW/cm² cooling requirement,

This contribution presents the R&D trajectory of ITS3, from sensor physics and radiation qualification to air-cooling mechanics and final qualification prototype.

Speaker: Naseem Bouchhar (Sejong University)

120 CEE experiment TPC tracking reconstraction

The Cooler-Storage-Ring External-target Experiment (CEE) is a spectrometer to study the properties of nuclear matter at high baryon density region. The CEE time projection chamber (TPC), which uses the state-of-the-art SAMPA electronics read-out chips is the key sub-detector of CEE. This talk presents the track-finding algorithm that is used for event reconstruction for the TPC detector at the CEE experiment. The algorithm is based on Cellular Automaton and Combinatorial Kalman filter techniques, which provides a good balance between speed and efficiency to find charged tracks and therefore meets the requirements of CEE experiment.

Speaker: Guo Aiqiang

121 Beam Telescope Characterisation of babyMOSS for the ALICE ITS3 Upgrade

The ALICE experiment at the Large Hadron Collider (LHC) currently uses the Inner Tracking System 2 (ITS2) for tracking during LHC Run 3. ITS2 is based on Monolithic Active Pixel Sensor (MAPS) technology, known as ALPIDE (ALICE Pixel Detector). During Long Shutdown 3 (LS3), scheduled for 2026–2030, the innermost three layers of ITS2 will be replaced by ITS3. The ITS3 upgrade relies on wafer-scale stitching, which enables sensors substantially larger than previous generations. Thinning these wafer-scale sensors to 50 μm allows them to be bent into a truly cylindrical structure. The first prototype built on this stitched-sensor technology is the Monolithic Stitched Sensor (MOSS), consisting of ten Repeated Sensor Units (RSUs). Each RSU is divided into top and bottom half-units fabricated with different pixel pitches, 18.0 μm and 22.5 μm, respectively, to study the impact of pixel density on performance. To evaluate sensor performance under realistic conditions, beam telescopes are used, comprising reference sensors for tracking, a scintillator for triggering, and a babyMOSS sensor as the Device Under Test (DUT). This setup extends the scope of sensor qualification beyond lab-based characterisation. This talk presents the design, implementation, and results of ITS3 beam tests carried out with beam telescopes, with emphasis on their relevance to the ongoing development of the ALICE ITS3 upgrade.

Speaker: Geunyoung Yang

122 From AC-LGAD Time Resolution to PID Reach at the EIC: Test-Beam and TCT Laser Studies for the ePIC Barrel Time-of-Flight

Author
Kanato Matsutani$^{1,2}$ for the ePIC Japan Group
$^1$Graduate School of Advanced Science and Engineering, Hiroshima University, Japan
$^2$WPI-SKCM2, Hiroshima University, Japan

Abstract
The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will collide polarized electrons with protons and nuclei to explore the partonic structure of matter. Hadron identification in the ePIC barrel relies on a time-of-flight layer (BTOF) of strip-type AC-coupled Low-Gain Avalanche Diodes (AC-LGADs) with 500 µm pitch and 1 cm long strips, with a per-hit timing requirement of 95 ps and a stretch goal of 40 ps. We evaluated strip AC-LGAD sensors through a beam test at KEK PF-AR with 2 GeV electrons and infrared laser TCT scans, and discuss how the measured time resolution maps onto the π/K separation reach. The beam test achieved about 60 ps per hit at -185 V, satisfying the requirement, after time-walk corrections using the pulse amplitude and the hit position reconstructed from signal sharing between neighboring strips. The TCT scans, which are free of ionization statistics, yield a per-channel resolution below 30 ps and characterize the signal propagation along the strip. The origin of the difference between the two measurements is under investigation, considering Landau fluctuations, the reference MCP-PMT contribution, and the smaller signal amplitude of the present sensors. We present these studies and the prospects toward the stretch goal.

Speaker: KANATO MATSUTANI (Hiroshima University)

matsutani_abst_ATHIC2026_final.pdf

123 Detector upgrade status of Korea FAZIA group and performance evaluation from the RAON proton beam test

A FAZIA (Forward-angle A and Z Identification Array) telescope consists of two silicon pad detectors and a CsI(Tl) scintillator. Using the ΔE–E correlation and pulse shape analysis (PSA), the FAZIA detector can identify charges up to Z = 52 and discriminate isotopes up to Z = 25.

Presently, the FAZIA upgrade project is ongoing with the goal of extending the beam-energy coverage and lowering the particle-identification threshold. Within this project, the Korean FAZIA group is taking a leading role in the development of silicon sensors with various thicknesses and improved Front-End Electronics (FEE) boards. Silicon sensors with thicknesses ranging from 115 to 750 μm have been successfully developed, and their energy resolution has been evaluated using an Am-241 alpha source. The newly designed FEE boards employ the latest Xilinx Kintex-7 FPGA with optimized VHDL firmware.

Recently, the Korean FAZIA group successfully assembled a FAZIA detector block consisting of 16 telescopes using the newly developed 100 μm and 675 μm silicon sensors together with the upgraded FEE boards. To evaluate the performance of the detector block, a proton beam test was performed using the cyclotron at RAON.

This presentation will introduce the current status of the detector development by the Korean FAZIA group and summarize the performance evaluation results obtained from the proton beam test at RAON.

Speaker: Mr Wonjun Jeong (Inha University)

Parallel 4

124 Onset of hydrodynamics in a strongly coupled system based on quantum many-body calculation

Onset of hydrodynamics in the hot medium created in relativistic heavy-ion collisions is a crucial theoretical question. Addressing this problem in a first-principle manner, requires a real-time, non-perturbative simulation of a large scale quantum system, as hydrodynamic behavior emerges only when approaching the continuum limit. The exponentially large Hilbert space of quantum states prevents an exact simulation on classical hardwares. To overcome such a difficulty, we perform such a simulation using the Tensor Network method, which enables simulations of a reduced representation space of large scale quantum many-body systems by keeping only the most essential quantum states contributing to macroscopic quantities.

We focus on the massive Schwinger model, a low-dimension analog of quantum chromodynamics (QCD), as it shares the important properties such as confinement and chiral symmetry breaking. Starting from an initial quantum state that mimics hard particle collisions, we observe the onset of hydrodynamic behavior that is consistent with the Bjorken-flow in all hydrodynamic degrees of freedom: energy density, fluid velocity, and bulk pressure. The time scale for the onset of hydrodynamics is found to be consistent with the thermalization time of the quantum distribution function. Both time scales are of the same order as the hydrodynamization time determined by fitting the experimental data, upon a physical matching that extrapolates the 1+1 dimensional Schwinger model to the 3+1 dimension QCD.

Speaker: Mr Shuzhe Shi (Tsinghua University)

125 Non-perturbative Dynamics of Holographic QCD under Extreme Conditions

Recently, we have conducted a series of studies on the non-perturbative dynamics of QCD matter under extreme conditions using a unified lattice-calibrated holographic framework. First, addressing the rotational response of pure gluonic matter, we established a rotation-magnetic correspondence and revealed a chromomagnetic-induced inertia inversion mechanism. We show that melting chromomagnetic flux tubes near the deconfinement temperature drive a negative Barnett effect and negative moment of inertia, an anomaly that vanishes at a critical velocity squared of approximately 0.1. Second, for finite-density systems, we constructed a thermodynamically self-consistent multi-charge model to resolve the ambiguity in critical endpoint location. Our results predict pronounced nonmonotonic shifts in the critical endpoint due to coupled electric and strange chemical potentials, and identify coherent dual-channel critical peaks in cumulant ratios at collision energies around 5 to 7 GeV. Third, regarding high-energy transport, we demonstrated that jet quenching parameters and parton energy loss exhibit sharp enhancements near the critical endpoint. Notably, heavy-quark drag transitions from collisional to radiative dominance with increasing velocity, while light-quark total energy loss is governed by stopping distance. These findings provide multi-dimensional theoretical benchmarks for mapping the QCD phase diagram in ongoing and future experiments.

Speaker: Zhibin Li (Zhengzhou University)

126 Quantum simulation of particle production and equilibration from classical fields

Understanding how highly-occupied quantum fields equilibrate is a central challenge in nonequilibrium quantum field theory, with direct relevance to the pre-equilibrium dynamics of relativistic heavy-ion collisions and the reheating epoch of the early Universe. Classical-statistical approaches capture the large-occupancy regime but cannot describe genuine quantum equilibration. Here we show that this problem is naturally amenable to quantum computation and perform first quantum simulations of particle production from classical fields in lattice λφ⁴ theory. Using coherent states as initial conditions, we find that particle production is accompanied by the equilibration of observables, which persists for timescales several times longer than the initial equilibration time before quantum Poincaré recurrences set in. Our results establish a first-principles route toward nonequilibrium quantum field theory on quantum computers and provide insight into the emergence of equilibrated states in isolated systems.

Speaker: Wenyang Qian (CCNU)

127 Probing the Neutron Skin with Extreme Collision Geometries in Heavy-Ion Collisions

Understanding how protons and neutrons are located differently in an atomic nucleus can provide fundamental information on nuclear structure and have far-reaching implications for astrophysics. A precise determination of this important difference, often quantified by the so-called neutron skin thickness, is challenging both theoretically and experimentally. Here we show how one can use a new category of observables in heavy ion collisions to probe the neutron skin thickness of nuclei like $^{208}Pb$ and $^{48}Ca$, by utilizing the asymmetry between neutrons and protons of spectator nucleons in super-central collisions as well as that of participant nucleons in peripheral collisions. Using quantitative simulations, we demonstrate their sensitivity and great potential in constraining neutron skin thickness for both $^{208}Pb$ and $^{48}Ca$ nuclei in these extreme event geometries. Furthermore, we propose asymmetric collisions between $^{48}Ca$ and $^{40}Ca$ nuclei as a unique and powerful way to nail down the neutron skin thickness.

Speaker: Dr Hui Zhang (South China Normal University/Institute of Quantum Matter)

128 Efficient Quantum Simulation of Quantum Chromodynamics

We present a novel quantum algorithmic framework for simulating Quantum Chromodynamics (QCD) on quantum computers. By employing the axial gauge ($A_3 = 0$) and the addition of non-local gauge fixings, this framework explicitly eliminates all local redundant gauge degrees of freedom. Within this formalism, we rigorously establish upper bounds on both the qubit overhead and the gate complexity of the time-evolution operator required for QCD simulation. We demonstrate that these resource requirements scale polynomially with the desired simulation precision $\varepsilon_s$, the lattice volume $\mathcal{V}$, the QCD coupling constant $g$, and the target physical energy scale $E$. For the first time, our work provides a rigorous theoretical proof of ``QCD can be simulated on quantum computers efficiently", laying a solid theoretical foundation for its realization on future fault-tolerant quantum architectures.

Speaker: Tianyin Li (RIKEN, iTHEMS)

129 Gluodynamics in accelerated frames using first-principles lattice simulations

At this conference, I will present our latest findings on the properties of gluodynamics in an accelerated frame of reference, investigated via first-principles lattice simulations. To study the accelerated system, we employ Rindler coordinates, wherein a comoving observer cannot receive signals from beyond the Rindler horizon. We investigate the confinement-deconfinement phase transition properties of a pure gauge theory (SU(3) color)—a gluon plasma—under weak acceleration. The system is probed using the Polyakov loop and its associated susceptibility, which are properly renormalized in accordance with the Rindler geometry. Acceleration induces a spatially inhomogeneous transition characterized by a temperature gradient consistent with the Tolman-Ehrenfest (TE) law. Within the studied acceleration regime, and in the vicinity of the critical temperature, our results reveal a weak violation of the TE law in the strongly interacting medium due to vector gluon fields. This deviation from the classical TE prediction, which increases with temperature, suggests a non-trivial modification for vector quantum fields such as gluons. This spatially inhomogeneous transition manifests as a crossover, whose width and height decrease with increasing acceleration. Furthermore, we demonstrate with high precision that the critical temperature remains unchanged compared to standard, non-accelerated gluodynamics.

Speaker: Jayanta Dey (BLTP JINR, Russia)

Abstract_Jayanta.pdf

130 Is the shear induced spin polarization non-dissipative?

The shear-induced polarization plays a crucial role in understanding the local polarization of Λ and Λ⎯ hyperons. A key puzzle is whether the shear-induced polarization is non-dissipative or not. In this work, we analyzed the shear-induced polarization and the anomalous Hall effects using the entropy flow and H-theorem introduced from quantum (chiral) kinetic theory. While the shear-induced polarization and the anomalous Hall effect do not directly contribute to the entropy production rate, the perturbations associated with the shear tensor lead to an increase in entropy, similar to the role of the shear tensor in classical kinetic theory. We also examined these effects within the framework of linear response theory using Zubarev's approach. These findings highlight the limitations of the current theoretical framework in fully characterizing the dissipative properties of these phenomena.

Speaker: 家荣 汪 (中国科学技术大学)

131 Spin Entanglement in QCD：from Non‑Equilibrium Scattering and Topological Fluctuations

Entanglement generated in the early stage of relativistic heavy-ion collisions (HIC) is considered a direct and fundamental source for understanding fast thermalization, entropy production, and evolution. Spin entanglement in QCD, arising from non-commutative geometric effects of quantum fields, provides a new avenue to explore the quantum informational footprint of the QCD topological vacuum structure and reveal potential origin of thermal entropy in chromodynamics. This work studies spin entanglement among quarks originating from two main sources: instanton(sphaleron)-induced effects, and gluon–quark scattering. Innovatively, we provide a method to extract spin entanglement in scattering processes respectively for light and heavy quark sector that corresponds to the two sources. We systematically calculate the entanglement in both cases and present results including concurrence and entropy as functions of the instanton parameter, physical mass, and momentum scale—aspects not explicitly discussed in previous studies. This directly reveals how the non-equilibrium nature of the system and field topology effects modulate spin entanglement, and clarifies the corresponding quantitative relationship between entanglement measures and core physical information related to flavor and scale. More importantly, this quantitatively explains the well-know sphaleron effect on QGP formation in early stage and its fast thermalization from spin d.o.f.
We further interpret the entanglement time scale, providing a quantitative comparison with the scrambling time, and clarify the quantum informational relations in the early-stage thermalization. Finally, we discuss some recent experimental interests and results in high-energy collisions.

Speaker: Guowei Yan (Sun Yatsen University)

132 Parton Pair Correlations in Direct-Photon Yield and Elliptic Flow

Direct photons escape the collision zone with negligible final-state interaction and retain information about the evolving QCD medium. Their low-momentum yield and elliptic flow $v_2$, however, remain challenging to describe simultaneously. Standard calculations treat the incoming partons as uncorrelated. We ask whether correlations surviving from the early non-equilibrium stage leave a measurable photon signal and contribute to the yield--flow tension.

We develop a general description of correlated parton pairs and follow their photon emission through a realistic collision evolution. Pair correlations do more than rescale the overall emission rate: their angular structure produces characteristic, sign-changing modifications of the photon spectrum. The yield and $v_2$ therefore probe complementary aspects of the same underlying correlations.

We compare the calculation with 0--20% PHENIX Au--Au data at $\sqrt{s_{NN}}=200$ GeV and ALICE Pb--Pb data at $2.76$ TeV. Within each collision system, one correlation pattern, kept unchanged between the yield and $v_2$ analyses, describes both observables more successfully than the uncorrelated baseline. This result supports partonic pair correlations as a candidate contribution to direct-photon phenomenology, without excluding other medium or emission effects. It also shows that photon measurements, although single-particle observables, can constrain two-particle structure and provide a new view of early-time hydrodynamization.

[1]Xingjian Lu, Shuzhe Shi. arXiv:2604.27926
[2]Xingjian Lu, Shuzhe Shi. arXiv:2606.02414
[3]Xingjian Lu, Shuzhe Shi. arXiv:2608.xxxxx

Speaker: Dr Xingjian Lu (Tsinghua University)

133 Drell-Yan process under an external magnetic field with full Landau levels

Strong magnetic fields generated in relativistic heavy-ion collisions may affect electromagnetic probes of strongly interacting matter. In this work, we investigate the Drell-Yan process under an external magnetic field by considering the full Landau-level structure of the initial-state quarks. Using a relativistic quantum field theoretical approach, we derive the transition amplitude for quark-antiquark annihilation into dilepton pairs, where the magnetic-field effects are incorporated through the Landau-level representation of fermion states. Beyond the lowest Landau level approximation, contributions from all Landau levels are included to study their impact on the dilepton production process. This study provides a systematic analysis of magnetic-field effects on Drell-Yan dilepton production and may contribute to understanding electromagnetic signals in heavy-ion collisions.

Speaker: Zhaolu OuYang

Monday 9 November

134 ALICE 3: Status and Prospects

Speaker: Minjung Kweon (Inha University)

135 The J-PARC-HI Project and Potential Hadron Physics with This and Related Projects

Speaker: Yudai Ichikawa (Tohoku University)

136 Status of RAON

Speaker: Kyungil Kim (IRIS/IBS)

137 High Intensity heavy-ion Accelerator Facility in China

Speaker: Jiancheng Yang (IMP)

Coffee Break

Awards & Flash Talks

Closing Ceremony

Lunch (Buffet)