Transport coefficients of the quark-gluon plasma at the critical point and across the first-order line
Transport coefficients of the quark-gluon plasma at the critical point and across the first-order line
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DOI：
10.1103/physrevd.106.034024
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发表时间：
2022-02
影响因子：
5
通讯作者：
Joaquin Grefa;M. Hippert;J. Noronha;J. Noronha-Hostler;I. Portillo;C. Ratti;R. Rougemont
中科院分区：
文献类型：
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作者：
Joaquin Grefa;M. Hippert;J. Noronha;J. Noronha-Hostler;I. Portillo;C. Ratti;R. Rougemont
自下而上的爱因斯坦-麦克斯韦-膨胀全息模型首次用于计算热富重子强耦合夸克-胶子等离子体在临界点以及穿过相图中的一级相变线的几个输运系数的行为。正在研究的可观测量包括剪切和体积粘度、重子扩散、热导率、喷射淬火参数$\hat{q}$，以及重夸克阻力和朗之万扩散系数。这些计算为这些系数提供了唯象学上有希望的估计，因为我们的模型除了自然地结合了夸克-胶子等离子体的近乎完美的流动性之外，还定量地再现了零重子密度和有限重子密度下的晶格 QCD 热力学结果。我们发现，随着重子密度的增加，重子电荷的扩散以及剪切和体积粘度受到抑制，这表明介质在大密度下变得更接近完美的流动性。另一方面，喷射淬火参数和重夸克动量扩散随着密度的增加而增强。当穿过一阶相变线时，可观测量显示出不连续间隙，同时在临界点处形成无限斜率。与不同传输系数相关的转变温度在交叉区域中不同，但发现在临界点处收敛。
A bottom-up Einstein-Maxwell-Dilaton holographic model is used to compute, for the first time, the behavior of several transport coefficients of the hot and baryon-rich strongly coupled quark-gluon plasma at the critical point and also across the first-order phase transition line in the phase diagram. The observables under study are of the shear and bulk viscosities, baryon diffusion, thermal conductivity, the jet quenching parameter $\hat{q}$, as well as the heavy-quark drag force and Langevin diffusion coefficients. These calculations provide a phenomenologically promising estimate for these coefficients, given that our model quantitatively reproduces lattice QCD thermodynamics results, both at zero and finite baryon density, besides naturally incorporating the nearly-perfect fluidity of the quark-gluon plasma. We find that the diffusion of baryon charge, and also the shear and bulk viscosities, are suppressed with increasing baryon density, indicating that the medium becomes even closer to perfect fluidity at large densities. On the other hand, the jet quenching parameter and the heavy-quark momentum diffusion are enhanced with increasing density. The observables display a discontinuity gap when crossing the first-order phase transition line, while developing an infinite slope at the critical point. The transition temperatures associated with different transport coefficients differ in the crossover region but are found to converge at the critical point.