论文标题
流体动力吸引子，用于全息速度Bjorken流量的速度
Hydrodynamic attractors for the speed of sound in holographic Bjorken flow
论文作者
论文摘要
平均能量动量张量的时间演变及其与能量密度的变化是在$ \ Mathcal {n} = 4 $ sym理论的远程平衡状态下计算的。该计算是按照全息进行的，我们考虑了解决方案中的能量密度轨迹的集合，该轨迹通过对散装时段的初始条件进行的小变化。我们认为，对角能量动量张量成分相对于能量密度的变化的正确解释是声音的平衡速度很大。我们证明了与相应的流体动力预测相当一致。我们发现，通过Borel重新召集，全息系统具有一种吸引人的声音纵向纵向，另一个横向向Bjorken扩展方向横向。各种初始流条件的吸引子时间表明，到达吸引子并不意味着或需要局部热平衡。在所研究的情况下，到达吸引子意味着流体动力（根据流体动力学大致进化），证明名称\ emph {流体动力吸引子}是合理的。
The time evolution of the averaged energy momentum tensor as well as its variation with energy density are calculated in a far-from-equilibrium state of $\mathcal{N}=4$ SYM theory undergoing a Bjorken expansion. The calculation is carried out holographically where we consider a collection of trajectories of the energy density in the space of solutions by small changes to the initial conditions of the bulk spacetime. We argue that the proper interpretation of the variation of the diagonal energy momentum tensor components with respect to the energy density is that of a far-from-equilibrium speed of sound. We demonstrate remarkable agreement with a corresponding hydrodynamic prediction. We find by Borel resummation that the holographic system has one attractor for this speed of sound longitudinal, and another transverse to the direction of Bjorken expansion. Attractor times for various initial flow conditions show that reaching an attractor does not imply or require local thermal equilibrium. In the cases studied, reaching an attractor implies hydrodynamization (quantities evolve approximately according to hydrodynamics), justifying the name \emph{hydrodynamic attractor }
