Vacuum polarization effects on nuclear matter and neutron stars

Abstract

Vacuum renormalization of relativistic nuclear field theory is studied for nuclear and neutron star matter in general equilibrium, and neutron stars. It is found that when the coupling constants are tightly constrained by the five saturation properties of nuclear matter, the binding, density, compression modulus, symmetry energy and effective nucleon mass, the theory with or without vacuum renormalization predicts an equation of state that differs in the two cases by only several percent over the entire density range of interest. If the effective mass and compression are not controlled, as in some works, the high density behavior is markedly different. The mass of a neutron star, even at the limiting mass, is not dominated by the dense matter at its center, half the mass being contributed by matter at densities less than about 3 ρ 0. The hyperon fraction of the limiting mass star is about 20%.