Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Quark Matter Research Center, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Phys Rev Lett. 2023 May 26;130(21):212303. doi: 10.1103/PhysRevLett.130.212303.
We investigate the response of the near-equilibrium quark-gluon plasma (QGP) to perturbation at nonhydrodynamic gradients. We propose a conceivable scenario under which sound mode continues to dominate the medium response in this regime. Such a scenario has been observed experimentally for various liquids and liquid metals. We further show that this extended hydrodynamic regime (EHR) indeed exists for both the weakly coupled kinetic equation in the relaxation time approximation (RTA) and the strongly coupled N=4 supersymmetric Yang-Mills (SYM) theory. We construct a simple but nontrivial extension of Müller-Israel-Stewart (MIS) theory-namely MIS*-and demonstrate that it describes the EHR response for both the RTA and SYM theory. This indicates that MIS* equations can potentially be employed to search for QGP EHR via heavy-ion collisions.
我们研究了近平衡夸克-胶子等离子体（QGP）对非流体动力学梯度扰动的响应。我们提出了一个可以想象的情景，在这个情景中，声波模式继续主导介质的响应。这种情况已经在各种液体和液态金属中得到了实验观察。我们进一步表明，这种扩展的流体动力学范围（EHR）确实存在于弛豫时间近似（RTA）下的弱耦合动力学方程和强耦合 N=4 超对称杨-米尔斯（SYM）理论中。我们构建了一个简单但非平凡的穆勒-以色列-斯图尔特（MIS）理论的扩展，即 MIS*-并证明它描述了 RTA 和 SYM 理论的 EHR 响应。这表明，MIS*方程可以用于通过重离子碰撞来寻找 QGP 的 EHR。
