Evolution of pressures and correlations in the glasma produced in high energy nuclear collisions
Evolution of pressures and correlations in the glasma produced in high energy nuclear collisions
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高能核碰撞产生的等离子体中压力和相关性的演变
DOI：
10.1103/physrevd.97.076004
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发表时间：
2018
影响因子：
5
通讯作者：
V. Greco
中科院分区：
文献类型：
--
作者：
M. Ruggieri;J.H. Liu;Oliva;G.X. Peng;V. Greco
我们考虑了具有高斯涨落的SU（2）玻璃，并通过数值求解格点上的经典Yang-Mills方程研究了它的演化。在第一项研究中忽略了纵向膨胀，我们跟踪了系统压力的演变，并计算了早期阶段波动的影响，直到t≈ 2 fm=c，这是玻璃与高能碰撞相关的时间范围。我们测量的比例的纵向的横向压力，PL=PT，我们发现，除非波动携带大量的能量密度在初始时间，他们不显着改变PL=PT的演变在早期阶段，该系统仍然相当各向异性。我们还测量了横向和沿着纵向的纵向场相关因子：虽然在初始时刻，场在横向上似乎是相关的，但这种相关关系在很早的阶段就消失了，并且横向上的相关长度增加。另一方面，我们发现的依赖性的规范不变相关的纵坐标，我们解释为部分损失的相关性引起的动力学，我们称之为规范不变字符串断裂。我们最后研究了涨落对纵向关联的影响：我们发现，色弦的破裂被涨落加速，并且等待足够长的时间涨落会导致色弦的完全破裂。
We consider the SU(2) glasma with Gaussian fluctuations and study its evolution by means of classical Yang-Mills equations solved numerically on a lattice. Neglecting in this first study the longitudinal expansion,wefollowtheevolutionofthepressuresofthesystemandcomputetheeffectofthefluctuations in the early stage up to t≈ 2 fm=c, that is the time range in which the glasma is relevant for high energy collisions. We measure the ratio of the longitudinal over the transverse pressure, PL=PT, and we find that unless the fluctuations carry a substantial amount of the energy density at the initial time, they do not change significantly the evolution of PL=PT in the early stage and that the system remains quite anisotropic. We also measure the longitudinal fields correlators both in the transverse plane and along the longitudinal direction: while at initial time fields appear to be anticorrelated in the transverse plane, this anticorrelation disappears in the very early stage, and the correlation length in the transverse plane increases. On the other hand, we find a dependence of the gauge invariant correlator on the longitudinal coordinate, which we interpret as a partial loss of correlation induced by the dynamics that we dub the gauge invariant string breaking. We finally study the effect of fluctuations on the longitudinal correlations: we find that string breaking is accelerated by the fluctuations and waiting for a sufficiently long time fluctuations lead to the complete breaking of the color strings.