It has been argued that the speed of sound of the strong interaction at high temperature can be measured using the variation of the mean transverse momentum with the particle multiplicity in ultracentral heavy-ion collisions. We test this correspondence by running hydrodynamic simulations at zero impact parameter with several equations of state, at several colliding energies from 0.2 TeV to 15 TeV per nucleon pair. The correspondence is found to be precise and robust for a smooth, boost-invariant fluid and an ideal detector. We discuss the differences between this ideal setup and an actual experiment. We conclude that the extraction of the speed of sound from data is reliable, and that the main uncertainty comes from our poor knowledge of the distribution of density fluctuations at the early stages of the collision.

中文翻译：

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使用平均横向动量获得相对论性超中心核-核碰撞中的声速


有人认为，在超中心重离子碰撞中，可以使用平均横向动量随粒子多重性的变化来测量高温下强相互作用的声速。我们通过在零影响参数下使用几个状态方程在每对核子从 0.2 TeV 到 15 TeV 的几个碰撞能量下运行流体动力学模拟来测试这种对应关系。发现这种对应关系对于光滑、增强不变的流体和理想的检测器来说是精确和稳健的。我们讨论了这种理想设置与实际实验之间的差异。我们得出的结论是，从数据中提取声速是可靠的，而主要的不确定性来自我们对碰撞早期密度波动分布的了解不足。