论文标题
使用Husimi功能$ - $半经典近似
Entropy production in longitudinally expanding Yang-Mills field with use of Husimi function$-$semiclassical approximation
论文作者
论文摘要
我们通过评估熵，颗粒数和压力各向异性的评估，研究了高度占用和弱耦合的阳米尔米尔山脉的可能的热化过程。系统的时间演变是通过在半经典近似中求解Wigner函数的运动方程，并模仿Glasma的初始条件。为了评估熵，我们采用Husimi-Wehrl（HW）熵，该熵是通过使用Husimi函数获得的，Husimi函数是通过涂抹Wigner函数给出的阳性半finite量子分布函数。通过$ g = 0.1 $和$ 0.2 $的数值计算，发现熵产生与粒子的创造一起出现在两个不同的阶段：在第一阶段，低纵向动量的粒子数和熵迅速生长。在第二阶段，较高的纵向动量模式的颗粒数和熵显示较慢。压力各向异性保留在我们的模拟中，这意味着该系统仍处于平衡状态。
We investigate the possible thermalization process of the highly occupied and weakly coupled Yang-Mills fields expanding along the beam axis through an evaluation of the entropy, particle number, and pressure anisotropy. The time evolution of the system is calculated by solving the equation of motion for the Wigner function in the semiclassical approximation with initial conditions mimicking the glasma. For the evaluation of the entropy, we adopt the Husimi-Wehrl (HW) entropy, which is obtained by using the Husimi function, a positive semidefinite quantum distribution function given by smearing the Wigner function. By numerical calculations at $g=0.1$ and $0.2$, the entropy production is found to occur together with the particle creation in two distinct stages: In the first stage, the particle number and the entropy at low longitudinal momenta grow rapidly. In the second stage, the particle number and the entropy of higher longitudinal momentum modes show slower increase. The pressure anisotropy remains in our simulation and implies that the system is still out-of-equilibrium.
