Longitudinal eccentricity decorrelations in heavy-ion collisions
Longitudinal eccentricity decorrelations in heavy-ion collisions
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DOI：
10.1103/physrevresearch.2.023362
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发表时间：
2020-03
影响因子：
4.2
通讯作者：
A. Behera;M. Nie;J. Jia
中科院分区：
文献类型：
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作者：
A. Behera;M. Nie;J. Jia
在重离子碰撞中，最终状态粒子的简谐流$V_n$由偏心向量${\mathcal{E}}_n$驱动，该向量描述了投射在横向平面上的初始火球的形状。最近人们认识到，火球的结构和形状，以及因此的${\mathcal{E}}_n$，在单个事件${\mathcal{E}}_n(\eta)$中以伪快度$\eta$波动。这导致不同$\eta$之间的偏心率去相关，驱动实验中观察到的纵向流动去相关。使用具有参数化纵向结构的 Glauber 模型，我们估计了偏心率去相关，并将其与椭圆流 $n=2$ 和三角形流 $n=3$ 的测量流量去相关系数相关联。我们从原子核的尺寸、不对称性和变形方面研究了偏心率去相关对碰撞系统选择的依赖性。我们发现这些核几何效应导致偏心率去相关性产生显着且特征性的模式，其描述了 Xe+Xe 和 Pb+Pb 碰撞之间的流动去相关性的测量比率。这些模式可以使用 RHIC 和 LHC 的现有实验数据进行搜索，如果得到证实，它们将提供一种方法来提高我们对重离子碰撞初始状态的理解。
In heavy-ion collisions, the harmonic flow $V_n$ of final-state particles are driven by the eccentricity vector ${\mathcal{E}}_n$ that describe the shape of the initial fireball projected in the transverse plane. It is realized recently that the structure and shape of the fireball, and consequently the ${\mathcal{E}}_n$, fluctuate in pseudorapidity $\eta$ in a single event, ${\mathcal{E}}_n(\eta)$. This leads to eccentricity decorrelation between different $\eta$, driving the longitudinal flow decorrelations observed in the experiments. Using a Glauber model with a paramerterized longitudinal structure, we have estimated the eccentricity decorrelations and related them to the measured flow decorrelation coefficients for elliptic flow $n=2$ and triangular flow $n=3$. We investigated the dependence of eccentricity decorrelations on the choice of collision system in terms of the size, asymmetry and deformation of the nuclei. We found that these nuclear geometry effects lead to significant and characteristic patterns on the eccentricity decorrelations, which describe the measured ratios of the flow decorrelations between Xe+Xe and Pb+Pb collisions. These patterns can be searched for using existing experimental data at RHIC and the LHC, and if confirmed, they will provide a mean to improve our understanding of the initial state of the heavy-ion collisions.