Paths to equilibrium in non-conformal collisions
Paths to equilibrium in non-conformal collisions
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DOI：
10.1007/jhep06(2017)154
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发表时间：
2017-06-29
影响因子：
5.4
通讯作者：
Zilhao, Miguel
中科院分区：
文献类型：
--
作者：
Attems, Maximilian;Casalderrey-Solana, Jorge;Zilhao, Miguel
我们扩展了我们以前的全息重离子碰撞的非共形理论的分析。我们提供了我们的数字代码的详细说明。我们研究在不同能量的碰撞规范理论与不同程度的非共形性。我们比较了四个弛豫时间：流体动力学时间（当流体力学变得适用），EoSization时间（当平均压力接近其平衡值），各向同性时间（当纵向和横向压力接近对方）和凝聚体弛豫时间（当期望值的标量算子接近其平衡值）。我们发现，这些过程可以发生在几个不同的顺序。特别是，冷凝物可以保持远离平衡，甚至在等离子体已经流体动力化和EoSized之后很长时间。我们还探讨了在流体动力学的能量密度的快度分布。这是远离升压不变的，其宽度随着非共形性的增加而减小。然而，在流体动力学的速度场几乎是完全升压不变的，不管非共形。这一结果可以用来约束重离子碰撞中流体动力学场的初始化。
We extend our previous analysis of holographic heavy ion collisions in non-conformal theories. We provide a detailed description of our numerical code. We study collisions at different energies in gauge theories with different degrees of non-conformality. We compare four relaxation times: the hydrodynamization time (when hydrodynamics becomes applicable), the EoSization time (when the average pressure approaches its equilibrium value), the isotropization time (when the longitudinal and transverse pressures approach each other) and the condensate relaxation time (when the expectation value of a scalar operator approaches its equilibrium value). We find that these processes can occur in several different orderings. In particular, the condensate can remain far from equilibrium even long after the plasma has hydrodynamized and EoSized. We also explore the rapidity distribution of the energy density at hydrodynamization. This is far from boost-invariant and its width decreases as the non-conformality increases. Nevertheless, the velocity field at hydrodynamization is almost exactly boost-invariant regardless of the non-conformality. This result may be used to constrain the initialization of hydrodynamic fields in heavy ion collisions.