Equation of state for neutron stars in SU(3) flavor symmetry

Abstract

Using several relativistic mean-field models (such as GM1, GM3, NL3, TM1, FSUGold, and IU-FSU) as well as the quark-meson coupling model, we calculate the particle fractions, the equation of state, the maximum mass, and radius of a neutron star within relativistic Hartree approximation. We also discuss in detail the role of nonlinear potentials involved in the mean-field models. In determining the couplings of the isoscalar, vector mesons to the octet baryons, we examine the extension of SU(6) spin-flavor symmetry to SU(3) flavor symmetry. Furthermore, we consider the strange (sigma* and phi) mesons and study how they affect the equation of state. We find that the equation of state in SU(3) symmetry can sustain a neutron star with mass of (1.8 similar to 2.1) M-circle dot, even if hyperons exist inside the core. It is noticeable that the strange vector (phi) meson and the variation of baryon substructure in matter also play important roles in supporting a massive neutron star.