We improve the excluded volume hadron resonances gas model (EHRG) to cure the acausal behavior of the sound velocity which is typical of excluded volume models. We achieve this by including temperature (T) and density ({\mu}) dependent hadron masses in the partition function of EHRG. The temperature and density dependent masses of the constituent quarks (u,d,s) and the light mesons are obtained within Nambu-Jona-Lasinio model while for the heavy hadrons we use linear scaling rule in terms of constituent quarks. With this improvement, we observe that the velocity of sound flattens at high temperature unlike old EHRG models where the sound velocity rises very rapidly at high temperatures which is the indication of its super-luminal behavior.
翻译:我们改进了被排除的体积反应气体模型(EHRG),以治愈在排除体积模型中典型的声速的因子行为。我们通过将温度(T)和密度(thmu})依赖的量积气模型纳入EHRG的分流功能来实现这一点。在Nambu-Jona-Lasinio模型中获得了组成部分夸克(u,d,s)的温度和密度依赖度质量和光介子,而对于重的散子,我们用线性裁量规则来测量组成方形。我们观察到,随着这一改进,高温下声平坦速度的速度与旧的EHRG模型不同,在高温下声音速度快速上升,这表明其超光性行为。