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arXiv 2205.01136nucl-thhep-ph
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慢的非平衡模态对QCD临界点附近动态结构因子的作用

Role of slow, out-of-equilibrium modes on the dynamic structure factor near the QCD critical point

Golam Sarwar, Md Hasanujjaman, Jan-e Alam

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21 pages, 7 figures
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摘要：

本文研究了为扩展QCD临界点附近流体动力学理论的有效性而引入的慢失平衡模（OEM）在动力学密度涨落功率谱上的作用。对于热力学的广泛性质不因OEM的引入而改变的情况，我们采用了慢模的运动方程。我们发现，扩展性条件提出了一个额外的约束与速度的四个分歧的OEM的耦合。在OEM存在下的动态结构因子（Snn）示出了四个洛伦兹峰，其不对称地位于$ω(\text{frequency})=0$附近，而在没有任何OEM存在下的动态结构因子示出了三个众所周知的洛伦兹峰。在OEM存在下峰的宽度减小。我们发现，非对称峰起源于流体动力学模式与平衡模式的耦合。它还表明，OEM有可以忽略不计的影响，如果一阶流体力学（相对论Navier-Stokes）使用。OEM的引入减少了Rayleigh峰的宽度，表明波动衰减率的降低，从而导致临界终点（CEP）的众所周知的特征减慢。

英文摘要：

The role of slow out of equilibrium modes (OEM), introduced to extend the validity of hydrodynamics near the QCD critical point on the power spectrum of dynamical density fluctuations has been studied. We have used the equation of motion of slow modes for the situation when the extensive nature of thermodynamics is not altered due to the introduction of OEM. We find that the extensivity condition puts an extra constraint on the coupling of OEM with the four divergence of velocity. The dynamic structure factor (Snn) in presence of the OEM shows four Lorentzian peaks asymmetrically positioned about $ω(\text{frequency})=0$, whereas the dynamic structure factor without the presence of any OEM shows three well-known Lorentzian peaks. The width of the peaks are reduced in presence of OEM. We find that the asymmetric peaks originate due to the coupling of the out-of-equilibrium modes with the hydrodynamic modes. It is also shown that the OEM has negligible effects on Snn if first order hydrodynamics (relativistic Navier-Stokes) is used. The introduction of OEM reduces the width of the Rayleigh peak indicating the reduction in the decay rate of the fluctuation which leads to slowing down, a well-known characteristics of the critical end point (CEP).

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