The freeze out of the expanding systems, created in relativistic heavy ion collisions, is discussed. We combine kinetic freeze out equations with Bjorken type system expansion into a unified model. The important feature of the proposed scenario is that physical freeze out is completely finished in a finite time, which can be varied from 0 (freeze out hypersurface) to infinity. The dependence of the post freeze out distribution function on the freeze out time will be studied. As an example, model is completely solved and analyzed for the gas of pions. We shall see that the basic freeze out features, pointed out in the earlier works, are not smeared out by the expansion of the system. The entropy evolution in such a scenario is also studied.
Nonequilibrium fixed points in longitudinally expanding scalar theories: infrared cascade, Bose condensation and a challenge for kinetic theory
In Phys. Rev. Lett. 114（2015）6，061601，我们报道了纵向扩展系统的新普适类，包括强相关的非阿贝尔等离子体和$N$分量自相互作用标量场理论。使用经典统计方法，我们发现，这些系统共享相同的自相似标度特性的范围很广的动量在一个限制，粒子弱耦合，但他们的占有率高。在这里，我们显着扩展了之前的工作，并进一步描述了两个自相似机制。其中之一发生在极高占位率的深红外（IR）区域，其中非平衡动力学导致形成玻色-爱因斯坦凝聚体。通用的IR标度指数和光谱指数表征的各向同性IR分布的一个有效的理论来自一个系统的大$N$展开在次到领先的顺序。值得注意的是，这个有效的理论可以被看作是一个顶点标记的动力学理论。另一种新的自相似机制出现在理论的硬物理尺度附近，只是在后来才出现。我们认为，红外动力学的重要作用，确保我们的标量和规范理论的结果的关键特征不能在传统的动力学理论框架一致地再现。
Transport equations of a consistent description of the kinetics and hydrodynamics of dense quantum systems. I: General approach within the frame of nonequilibrium thermo field dynamics
Molecular dynamics description of an expanding $q$/$\bar{q}$ plasma with the Nambu--Jona-Lasinio model and applications to heavy ion collisions at RHIC and LHC energies
Correspondence between Israel-Stewart and first-order causal and stable hydrodynamics for Bjorken-expanding baryon-rich systems with vanishing particle masses
Kinetic description of Bose-Einstein condensation with test particle simulations
本文给出了超相对论重离子碰撞早期产生的胶子在非热平衡状态下的玻色-爱因斯坦凝聚的动力学描述。玻色子向平衡态的动力学过程由包含玻色因子的玻尔兹曼方程描述。为了求解含有玻色-爱因斯坦凝聚体的Boltzmann方程，我们进一步发展了动力学输运模型BAMPS（Boltzmann Approach of MultiParton Scatterings）。在这项工作中，我们证明了正确的数值实现，通过比较最终的数值结果与预期的解决方案，在热平衡系统的存在和不存在的玻色-爱因斯坦凝聚体。此外，我们还详细研究了过填充胶子系统中凝聚的起始。我们发现，无论是预期的幂律标度表示的粒子和能量级联观察计算胶子分布函数在红外和中等动量区域，分别。此外，硬标度的时间演化在时间窗口中表现出幂律标度，这表明在该时间段内分布函数近似自相似。
