Strongly coupled matter near phase transition

Abstract

In the Hartree approximation of Cornwall-Jackiw-Tomboulis (CJT) formalism of the real scalar field theory, we show that for the strongly coupled scalar system near phase transition, the shear viscosity over entropy density is small, however, the bulk viscosity over entropy density is large. The large bulk viscosity is related to the highly nonconformal equation of state. It is found that the square of the sound velocity near phase transition is much smaller than the conformal value 1/3, and the trace anomaly at phase transition deviates far away from 0. These results agree well with the lattice results of the complex QCD system near phase transition.