论文标题

$ \ sqrt {s _ {_ {\ rm nn}}}} = $ 27和62 GEV的重型离子碰撞的初始状态模型的基准

A benchmark of initial state models for heavy-ion collisions at $\sqrt{s_{_{\rm NN}}}=$ 27 and 62 GeV

论文作者

Cimerman, Jakub, Karpenko, Iurii, Tomášik, Boris, Trzeciak, Barbara Antonina

论文摘要

用流体动态方法在Rhic Beam Energy扫描程序中对相对论重型离子碰撞的描述提出了几个挑战,其中之一是复杂的几何形状和较长的杂水动力学阶段的持续时间。因此,在Rhic Beam Energy扫描能量上进行重型离子碰撞的现有流体动力学模型依赖于相当复杂的初始状态,例如URQMD级联或多流体动力学。在这项研究中,我们表明,在$ \ mbox {$ \ mbox {$ \ sqrt {s _ {_ {_ {\ rm nn}}}} $和62.4〜GEV时,可以使用功能更简单,非动态的初始状态用于$ \ mbox {$ \ mbox {$ \ sqrt {$ \ sqrt {$ \ sqrt {$ \ sqrt {$ \ sqrt {$ \ sqrt {我们根据Monte Carlo Glauber模型(Glissando 2)和$ \ sqrt {T_A T_B} $ ANSATZ调整初始状态,基于厚度的减小(T $ _ {\ rm R} $ ENTO $ $ P = 0 $),扩展到较长的方向和有限的baryon baryon Baryon浓度。我们发现,当两种碰撞能量在两个碰撞能量下,两种初始状态在与3D事件 - 事件粘性动力学 +级联模型耦合时,都会导致基本实验数据的总体公平再现:伪率分布,横向动量光谱和椭圆流。鉴于$ \ sqrt {t_a t_b} $ ansatz在功能上与EKRT和IP-GLASMA模型相似,这是一个相当令人惊讶的,这在更大的能量上取得了成功,并且依赖于初始状态的党派图片。

Description of relativistic heavy-ion collisions at the energies of RHIC Beam Energy Scan program with fluid dynamic approach poses several challenges, one of which being a complex geometry and a longer duration of the pre-hydrodynamic stage. Therefore, existing fluid dynamic models for heavy-ion collisions at the RHIC Beam Energy Scan energies rely on rather complex initial states, such as UrQMD cascade or multi-fluid dynamics. In this study, we show that functionally simpler, non-dynamical initial states can be employed for the fluid dynamical simulations of Au-Au collisions at $\mbox{$\sqrt{s_{_{\rm NN}}}$}=27$ and 62.4~GeV. We adapt the initial states based on Monte Carlo Glauber model (GLISSANDO 2) and $\sqrt{T_A T_B}$ ansatz based on reduced thickness (T$_{\rm R}$ENTo $p=0$), extended into the longitudinal direction and finite baryon density. We find that both initial states, when coupled to a 3D event-by-event viscous fluid dynamic + cascade model, result in an overall fair reproduction of basic experimental data: pseudorapidity distributions, transverse momentum spectra and elliptic flow, at both collision energies. This is a rather surprising, given that the $\sqrt{T_A T_B}$ ansatz is functionally similar to the EKRT and IP-Glasma models, which are successful at much larger energies and rely on a partonic picture of the initial state.

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