Relativistic Mean Field Approach with Chiral Symmetry Breaking and Quark Confinement in the light of Astrophysical Observations

Abstract

We perform a Bayesian analysis of a relativistic mean-field approach, which is an implementation of the chiral confining model with both chiral symmetry breaking and confinement effects, and which was recently proven to reproduce well the ground state properties of finite nuclei. We additionally explore the impact of couplings between $ρ$ and $ω$ mesons as well as a non-linear $ω$ coupling. Our models are simultaneously constrained by nuclear matter properties near saturation density, multi-messenger neutron star astrophysical observations, and/or lattice QCD predictions of the nucleon mass. It exhibits tension in simultaneously reproducing the $\sim 2M_{\odot}$ massive NS and the tidal deformability inferred from GW170817. We show that an additional $ωρ$ coupling, favored by Bayes factor analysis, substantially alleviates this tension, while adding a non-linear $ω$ self-interaction is not necessary for the RMF-CC model. Owing to the strong constraints on the scalar sector imposed by chiral dynamics and the softening of the equation of state at high densities induced by our treatment of confinement, the RMF-CC approach favors stiff equations of state. Since we do not consider phase transition in the core of neutron stars, this stiffening is obtained with large values of the incompressibility modulus of about $\sim300$ MeV. We finally compare the well-known RMF model with RMF-CC models with the same constraints, and we obtain a preference for the RMF model in the absence of a phase transition in the core of neutron stars.