Examining the event-shape-dependent modifications to charged-particle transverse momentum spectra and elliptic flow in p -Pb collisions at energies available at the CERN Large Hadron Collider
Examining the event-shape-dependent modifications to charged-particle transverse momentum spectra and elliptic flow in p -Pb collisions at energies available at the CERN Large Hadron Collider
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DOI：
10.1103/physrevc.102.044901
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发表时间：
2020-08
影响因子：
3.1
通讯作者：
S. Kar;S. Choudhury;Xiaoming Zhang;D. Zhou
中科院分区：
文献类型：
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作者：
S. Kar;S. Choudhury;Xiaoming Zhang;D. Zhou
在质子-质子(Pp)或质子-原子核(p-A)碰撞等小系统中，集体动力学的所谓签名仍然缺乏明确的理解。尽管数据与流体动力学模型在定性和/或定量上是一致的，但小系统中的谐和流动是否与由初始几何形状驱动的流体动力集体的共同物理图景有关仍不清楚。在目前的工作中，我们旨在通过引用事件形状工程(ESE)的新概念来解决这个问题，该概念已被用于在高能重离子碰撞中获得对初始几何的一些控制。我们通过构造一个参考流向量$Q_{2}$来使用ESE，该向量允许基于事件的椭圆度来刻画事件。在3+1D粘性流体动力学模型EPOS3模拟的数据集上，我们研究了5.02TeV的p-Pb碰撞中，包括横向动量($p_(T)$)谱和$p_(T}$-微分的$v_(2)$)等一些总体性质随事件形状的变化。根据不同大小的参考流矢量选择事件，我们观察到事件形状引起的修改作为事件形状选择的函数的提示，但带电粒子的包含谱似乎对这种事件形状选择不敏感。
Purported signatures of collective dynamics in small systems like proton-proton (pp) or proton-nucleus (p-A) collisions still lack unambiguous understanding. Despite the qualitative and/or quantitative agreement of the data to hydrodynamic models, it has remained unclear whether the harmonic flows in small systems relate to the common physical picture of hydrodynamic collectivity driven by the initial geometry. In the present work, we aim to address this issue by invoking a novel concept of Event Shape Engineering (ESE), which has been leveraged to get some control of the initial geometry in high-energy heavy-ion collisions. We utilise ESE by constructing a reference flow vector, $q_{2}$ that allows to characterise an event based on it's ellipticity. Applying this technique on a data set, simulated from a 3+1D viscous hydrodynamic model EPOS3, we study the event-shape dependent modifications to some of the bulk properties like, inclusive transverse momentum ($p_{T}$) spectra and $p_{T}$-differential $v_{2}$ for p-Pb collisions at 5.02 TeV. Selecting events on the basis of different magnitudes of reference flow vector $q_{2}$, we observe a hint of event-shape induced modifications of $v_{2}$ as a function of $p_{T}$ but, the inclusive $p_{T}$-spectra of charged particles seem to be insensitive to this event-shape selection.