AI 中文总结
本研究利用EPOS4分析不同能量的Pb-Pb、Xe-Xe、O-O碰撞，结合UrQMD模型研究软QGP信号，评估EPOS4集体动力学，为揭示QGP性质提供定量指导。
AI 中文摘要
重离子碰撞中的集体膨胀与流体动力学演化已得到充分证实，但高能下小系统是否产生飞米尺度的夸克胶子等离子体（QGP）液滴仍是一个基础开放性问题。本文利用EPOS4报告了对质心系能量√s_NN=5.02TeV的铅-铅（Pb-Pb）碰撞、√s_NN=5.44TeV的氙-氙（Xe-Xe）碰撞及√s_NN=5.36TeV的氧-氧（O-O）碰撞的分析，以开展预测与后预测研究。将结果与ALICE合作组的Pb-Pb、Xe-Xe碰撞数据进行对比，研究了带电粒子多重数（dN_ch/dη）、π介子（π±）、K介子（K±）及质子（p(overline{p})）的横动量（p_T）谱。研究发现，引入强子后处理模型UrQMD（超相对论量子分子动力学）是正确描述重子产额的必要条件；还通过归一化横动量关联函数√⟨⟨Δp_{T,i}Δp_{T,j}⟩⟩/⟨⟨p_T⟩⟩研究了p_T涨落；最后计算了各向异性流谐波v₂{2}、v₃{2}随p_T和中心度的变化关系。由于EPOS4在流可观测量方面尚未得到广泛研究，本研究对其集体动力学进行了重要评估，在有实验数据的地方均将结果与实验对比，整体上实现了从Pb-Pb到Xe-Xe再到O-O碰撞的软可观测量的统一描述，为这类碰撞如何揭示QGP性质提供了定量指导。
英文摘要
The collective expansion and hydrodynamic evolution in heavy-ion collisions is well-established. However, whether femtometer-scale droplets of QGP are produced in small systems at high energies remains a fundamental open question. Analysis of Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV, Xe$-$Xe at $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV and O$-$O collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.36 TeV using EPOS4 is reported to make predictions and postdictions. The results are compared with ALICE data for Pb$-$Pb and Xe$-$Xe collisions. Charged particle multiplicity (d$N_{\mathrm{ch}}$/d$η$), transverse-momentum ($p_{\mathrm{T}}$) spectra for pions ($π^{\pm}$), kaons ($K^{\pm}$), and protons ($\text{p}(\overline{\text{p}})$) are studied. The inclusion of hadronic afterburner, UrQMD (Ultra-relativistic Quantum Molecular Dynamics) is found to be necessary to correctly describe baryon yields. $p_{\mathrm{T}}$-fluctuations are also studied via normalized $p_{\mathrm{T}}$ correlator, $\sqrt{\langle \langle Δp_{\mathrm{T},i}Δp_{\mathrm{T},j} \rangle \rangle}\mathrm{/} \langle \langle p_{\mathrm{T}} \rangle \rangle$. Lastly, anisotropic flow harmonics ($v_{\mathrm{2}} \{2\}$, $v_{\mathrm{3}} \{2\}$) are computed as a function of $p_{\mathrm{T}}$ and centrality. Since EPOS4 has not been extensively studied for flow observables, this study thereby provides a non-trivial assessment of its collective dynamics. The results are compared with experiment wherever data is available. Taken together, this study provides a unified description of soft observables from Pb$-$Pb through Xe$-$Xe down to O$-$O and offer quantitative guidance on how such collisions may inform of the properties of the QGP.
Journal refPhys.Rev.C 114 (2026) 2, 025203
