Speed of sound in QCD matter

We systematically investigate the speed of sound in QCD matter under different conditions in the grand canonical ensemble within the Polyakov loop improved Nambu-Jona-Lasinio (PNJL) model. The numerical results indicate that the dependence of speed of sound on parameters like temperature and chemical potential can be indicative of QCD phase transition. Some new features of speed of sound are discovered, for instance, the hierarchy of sound velocity for u(d) and s quark at low temperature with the increasing chemical potential and the squared sound velocity approaching to almost zero in the critical region. We also formulate the relations between differently defined sound velocity using the fundamental thermodynamic relations. Some conclusions derived are useful for hydrodynamics simulation and calculation of transport coefficient of bulk viscosity.

Automated summary

In this study, the speed of sound in QCD matter was systematically investigated using the PNJL model in the grand canonical ensemble. The results indicate that the speed of sound can be indicative of QCD phase transition and new features of sound velocity were discovered. Furthermore, the relations between differently defined sound velocity were formulated, providing useful conclusions for hydrodynamics simulation and calculation of transport coefficient of bulk viscosity.