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arXiv 2006.01090hep-phhep-thnucl-th
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高能核碰撞早期拓扑荷和手征密度的涨落

Fluctuations of topological charge and chiral density in the early stage of high energy nuclear collisions

Moran Jia, Junhong Liu, Hongfei Zhang, Marco Ruggieri

摘要:

本文系统地研究了高能核碰撞早期的拓扑电荷密度和手征密度关联:初始条件由McLerran-Venugopalan模型给出,胶子场的演化由经典的Yang-Mills方程给出,直到适当的时间$τ\approx 1$ fm/c,对于$SU(2)$演化粒子.拓扑荷与规范不变量$\bm E \cdot \bm B$有关,其中$\bm E$和$\bm B$表示色电场和色磁场,而手征密度通过量子色动力学的手征反常产生。我们研究了相关长度与碰撞能量的关系,以及相关区域如何在横向平面中随着适当的时间增长,以实现增强不变的纵向扩展。我们估计这两个量的相关长度,在一个短暂的瞬态结果的顺序的典型的能量尺度的模型,即反饱和尺度。我们估计适当的时间形成一个稳定的状态,在该状态中,每单位快度的横向平面中的手征密度的生产减慢,以及手征密度的量,将存在于经典杨-米尔斯演化和相对论运输或水之间的切换时间的夸克-胶子等离子体阶段。

英文摘要:

We study systematically the topological charge density and the chiral density correlations in the early stage of high energy nuclear collisions: the intial condition is given by the McLerran-Venugopalan model and the evolution of the gluon fields is studied via the Classical Yang-Mills equations up to proper time $τ\approx 1$ fm/c for an $SU(2)$ evolving Glasma. Topological charge is related to the gauge invariant $\bm E \cdot \bm B$ where $\bm E$ and $\bm B$ denote the color-electric and color-magnetic fields, while the chiral density is produced via the chiral anomaly of Quantum Chromodynamics. We study how the correlation lengths are related to the collision energy, and how the correlated domains grow up with proper time in the transverse plane for a boost invariant longitudinal expansion. We estimate the correlation lengths of both quantities, that after a short transient results of the order of the typical energy scale of the model, namely the inverse of the saturation scale. We estimate the proper time for the formation of a steady state in which the production of the chiral density in the transverse plane per unit rapidity slows down, as well as the amount of chiral density that would be present at the switch time between the Classical Yang-Mills evolution and the relativistic transport or hydro for the quark-gluon plasma phase.

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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