发表机构
Henan Normal University; Institute of Nuclear Science and Technology, Henan Academy of Sciences; Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), and Institute of Modern Physics, Fudan University; Shanghai Research Center for Theoretical Nuclear Physics, NSFC and Fudan University（河南师范大学; 河南省科学院核科学和技术研究所; 复旦大学现代物理研究所及核物理与离子束应用教育部重点实验室; 国家自然科学基金委与复旦大学理论物理联合研究中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究用 JAM2 输运模型计算 Au+Au 碰撞的平均-$p_T$ 涨落，发现 $k_2$ 随中心性增加而减小，并给出粒子种类依赖的关联子预测，为理解初始态涨落演化提供参考。
AI 中文摘要
逐事件平均-$p_T$ 涨落探测初始态涨落及其通过重离子碰撞动力学的演化。我们使用 JAM2 在 RQMDv 平均场模式及 MH2 参数化下，研究了 $\sqrt{s_{\rm NN}}=3.0$--$19.6$ GeV 的 Au+Au 碰撞中的二阶平均-$p_T$ 涨落。该模型定性地重现了所测量的识别粒子 $p_T$ 谱，为涨落分析提供了单粒子基线。标度涨落 $k_2$ 随 $\langle N_{\rm part}\rangle$ 增加而减小，并在 7.7--19.6 GeV 下与现有测量结果大体一致，而其计算的中心性依赖性在 3.0--4.5 GeV 下强于数据。对于质子加反质子组合样本，未归一化关联子 $\langle c_2\rangle$ 为正且大于带电π介子的相应值。带电π介子关联子 $\langle c_2\rangle$ 在 3.0 和 3.5 GeV 的大多数中心性区间内为负或与零一致，在 4.5 GeV 时变为弱正，并在更高能量下保持为正。其能量演化类似于反应平面椭圆流的改变，但这种比较并未确立共同的微观起源。这些计算在无显式部分子阶段的输运模型内提供了依赖粒子种类的预测。分离平均场、再散射和旁观者相互作用的贡献需要对输运动力学进行受控变化。
英文摘要
Event-by-event mean-$p_T$ fluctuations probe initial-state fluctuations and their evolution through the dynamics of heavy-ion collisions. We study second-order mean-$p_T$ fluctuations in Au+Au collisions at $\sqrt{s_{\rm NN}}=3.0$--$19.6$ GeV using JAM2 in the RQMDv mean-field mode with the MH2 parameterization. The model qualitatively reproduces the measured identified-particle $p_T$ spectra, providing a single-particle baseline for the fluctuation analysis. The scaled fluctuation $k_2$ decreases with increasing $\langle N_{\rm part}\rangle$ and shows broad agreement with the available measurements at 7.7--19.6 GeV, whereas its calculated centrality dependence is stronger than that in the data at 3.0--4.5 GeV. For the combined proton-plus-antiproton sample, the unnormalized correlator $\langle c_2\rangle$ is positive and larger than that for charged pions. The charged-pion correlator $\langle c_2\rangle$ is negative or consistent with zero over most centrality intervals at 3.0 and 3.5 GeV, becomes weakly positive at 4.5 GeV, and remains positive at higher energies. Its energy evolution resembles the change in the reaction-plane elliptic flow, but this comparison does not establish a common microscopic origin. These calculations provide species-dependent predictions within a transport model without an explicit partonic stage. Isolating the contributions of mean fields, rescattering, and spectator interactions requires controlled variations of the transport dynamics.
Comments8 pages, 5 figures
