Equation of State for Strange Quark Matter in a Separable Model

Abstract

We present the thermodynamics of a nonlocal chiral quark model with separable 4-fermion interaction for the case of U(3) flavor symmetry within a functional integral approach. The four free parameters of the model are fixed by the chiral condensate, and by the pseudoscalar meson properties (pion mass, kaon mass, pion decay constant). We discuss the T=0 equation of state (EoS) which describes quark confinement (zero quark matter pressure) below the critical chemical potential mu_c=333 MeV. The new result of the present approach is that the strange quark deconfinement is separated from the light quark one and occurs only at a higher chemical potential of mu_{c,s}=492 MeV. We compare the resulting EoS to bag model ones for two and three quark flavors, which have the phase transition to the vacuum with zero pressure also at mu_c. We study quark matter stars in general relativity theory assuming beta-equilibrium with electrons and show that for configurations with masses close to the maximum of stability at M=1.62 ... 1.64 M_{solar} strange quark matter can occur.