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arXiv 1808.06342nucl-thnucl-ex
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中心Au+Au碰撞在$E_{lab}$ = 1.23 GeV $/$核子的重子数的累积揭示了核平均场势

The cumulants of the baryon number from central Au+Au collision at $E_{lab}$= 1.23 GeV$/$nucleon reveal the nuclear mean-field potentials

Yunxiao Ye, Yongjia Wang, Jan Steinheimer, Yasushi Nara, Hao-jie Xu, Pengcheng Li, Dinghui Lu, Qingfeng Li, Horst Stoecker

摘要:

相对论性重离子碰撞中重子数的涨落是探索QCD相图结构的一个很有希望的观测。中能($\sqrt{s_{\textrm{NN}}} < 7$ GeV)重离子碰撞中的累积量比至今还没有研究过。本文研究了平均场势和成团效应对1.23 GeV $/$核子能量下Au+Au碰撞中重子和质子数分布累积比的影响。利用超相对论量子分子动力学(UrQMD)和JAM模型计算了不同平均场势下的累积量。结果表明,累积量比具有很强的时间依赖性。在初始阶段,势对动量空间中粒子多重数涨落的影响相对较弱。平均场增强了膨胀阶段的涨落,特别是对于小的快度接受窗口。与所有重子相比,自由质子累积量比的增强被强烈抑制。平均场势和团簇效应对中能累积量比的测量起着重要的作用。

英文摘要:

Fluctuations of the baryon number in relativistic heavy-ion collisions are a promising observable to explore the structure of the QCD phase diagram. The cumulant ratios in heavy ion collisions at intermediate energies ($\sqrt{s_{\textrm{NN}}} < 7$ GeV) have not been studied to date. We investigate the effects of mean field potential and clustering on the cumulant ratios of baryon and proton number distributions in Au+Au collisions at beam energy of 1.23 GeV$/$nucleon as measured by the HADES Collaboration at GSI. Ultrarelativistic Quantum Molecular Dynamics (UrQMD) and the JAM model are used to calculate the cumulants with different mean field potentials. It is found that the cumulant ratios are strongly time dependent. At the early stage, the effects of the potentials on the fluctuations of the particle multiplicity in momentum space are relatively weak. The mean fields enhance the fluctuations during the expansion stage, especially for small rapidity acceptance windows. The enhancement of cumulant ratios for free protons is strongly suppressed as compared to that for all baryons. The mean field potentials and the clustering play an important role for the measured cumulant ratios at intermediate energy.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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