论文标题
在扩展等离子体中，远程平衡的慢速模式和动量各向异性
Far-from-equilibrium slow modes and momentum anisotropy in expanding plasma
论文作者
论文摘要
重型离子碰撞中粒子产生的动量分布编码有关早期夸克 - 杜伦等离子体中热化过程的信息。我们使用动力学理论来研究具有各向异性动量空间分布的扩展等离子体的远距离均衡进化。我们从该分布矩的演变中确定了远距离平衡等离子体中缓慢和快速的自由度。在后期，慢速模式对应于自由度的流体动力学程度，并且自然地从快速模式下，放松时间的倒数$τ_r^{ - 1} $。但是，在早期，有无限数量的慢速模式，其间隙与时间成反比，$τ^{ - 1} $。从慢速模式的演变中，我们将远程平衡吸引子的范式推广到能量量张量的矢量和张量成分，甚至是分布功能的较高矩，这些分布功能不属于流体动力学进化的一部分。我们预测，初始状态动量各向异性在远距离平衡阶段衰减缓慢，并且可能会持续到放松时间为止。
The momentum distribution of particle production in heavy-ion collisions encodes information about thermalization processes in the early-stage quark-gluon plasma. We use kinetic theory to study the far-from-equilibrium evolution of an expanding plasma with an anisotropic momentum-space distribution. We identify slow and fast degrees of freedom in the far-from-equilibrium plasma from the evolution of moments of this distribution. At late times, the slow modes correspond to hydrodynamic degrees of freedom and are naturally gapped from the fast modes by the inverse of the relaxation time, $τ_R^{-1}$. At early times, however, there are an infinite number of slow modes with a gap inversely proportional to time, $τ^{-1}$. From the evolution of the slow modes we generalize the paradigm of the far-from-equilibrium attractor to vector and tensor components of the energy-momentum tensor, and even to higher moments of the distribution function that are not part of the hydrodynamic evolution. We predict that initial-state momentum anisotropy decays slowly in the far-from-equilibrium phase and may persist until the relaxation time.
