Chiral phase transition and dynamical properties of quarks at finite temperature and density: Application of the “thermo-field dynamics” to the SU(3) Nambu-Jona-Lasinio model with instanton effects

Abstract

The properties of quarks in hot and/or dense matter are studied using the Nambu-Jona-Lasinio model with instanton effects. Thermo-field dynamics is applied to this model as a useful framework to present the unified description of quarks and nuclear matters at zero and non-zero temperatures. Especially, a four-dimensional cut-off parameter can be introduced transparently. The framework of this thermo-field dynamics is also discussed. We study the chiral symmetry in a finite temperature and/or density system. The dynamical quark masses are obtained up to a temperature of T = 400 MeV and a density of 10 times of the nuclear saturation density for nuclear and neutron matters. Furthermore, we examine the instanton effects in the nuclear medium and discuss s s content in the nucleon for nuclear and neutron matters.