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arXiv 2201.07962hep-phnucl-th
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重离子与EPOS碰撞中两粒子源函数的逐事件研究

Event-by-event investigation of the two-particle source function in heavy-ion collisions with EPOS

Dániel Kincses, Maria Stefaniak, Máté Csanád

摘要:

探索粒子(如π介子或K介子)的对源函数的形状一直是重离子物理学的一个重要目标,为了理解非高斯行为实验观察背后的物理学,人们已经做出了大量努力。在实验中,由于没有直接测量的源函数是可能的,量子统计动量相关性被用来获得有关的粒子发射源的时空几何信息。事件发生器,如EPOS,但是,提供了直接访问的冻结出坐标的最终状态的粒子,从而源函数可以构建和研究。EPOS模型是一个复杂的混合模型,其中系统的初始阶段演化由基于Parton的Gribov-Regge理论控制,随后利用流体动力学演化,然后是强子化和强子动力学。EPOS已经被证明成功地描述了重子化学势接近于零的系统的几种不同的实验观察,但到目前为止,源的形状尚未被详细探索。本文讨论了由EPOS模型产生的$\sqrt{s_{NN}}$ = 200 GeV Au+Au碰撞中两粒子源函数的逐事件分析。我们发现,当利用模型的所有阶段时,Lévy形分布(与高斯分布不同)提供了对单个事件中源形状的良好描述。因此,很明显,在成对分布中产生非高斯特征的不是事件平均。在此基础上,我们确定了作为事件中心性和粒子动量的函数的源的Lévy参数。

英文摘要:

Exploring the shape of the pair-source function for particles such as pions or kaons has been an important goal of heavy-ion physics, and substantial effort has been made in order to understand the underlying physics behind the experimental observations of non-Gaussian behavior. In experiments, since no direct measurement of the source function is possible, quantum-statistical momentum correlations are utilized to gain information about the space-time geometry of the particle emitting source. Event generators, such as EPOS, however, provide direct access to the freeze-out coordinates of final state particles, and thus the source function can be constructed and investigated. The EPOS model is a sophisticated hybrid model where the initial stage evolution of the system is governed by Parton-Based Gribov-Regge theory, and subsequently a hydrodynamic evolution is utilized, followed by hadronization and hadron dynamics. EPOS has already proven to be successful in describing several different experimental observations for systems characterized by baryon chemical potential close to zero, but so far the source shape has not been explored in detail. In this paper we discuss an event-by-event analysis of the two-particle source function in $\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions generated by the EPOS model. We find that when utilizing all stages of the model, Lévy-shaped distributions (unlike Gaussian distributions) provide a good description of the source shape in the individual events. Hence it is clear that it is not the event averaging that creates the non-Gaussian features in the pair distributions. Based on this observation, we determine Lévy-parameters of the source as a function of event centrality and particle momentum.

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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