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 (${\ensuremath{\sigma}}^{*}$ and $\ensuremath{\phi}$) 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 $(1.8\ensuremath{\sim}2.1){M}_{\ensuremath{\bigodot}}$, even if hyperons exist inside the core. It is noticeable that the strange vector ($\ensuremath{\phi}$) meson and the variation of baryon substructure in matter also play important roles in supporting a massive neutron star.