Relativistic mean-field model with density- and isospin-density-dependent couplings

TL;DR

This paper develops a new relativistic mean-field equation of state for dense matter with hyperons, incorporating density and isospin dependence, constrained by multiple nuclear and astrophysical data sources, to better model neutron star properties.

Contribution

It introduces a novel density- and isospin-dependent coupling scheme in the RMF model, constrained by Bayesian analysis with diverse experimental and theoretical data.

Findings

EoS satisfies neutron star mass-radius constraints from NICER and GW170817

Provides a comprehensive general-purpose EoS including hyperons and nuclear statistical equilibrium

Addresses the hyperon puzzle in neutron star modeling

Abstract

We present a new hadronic EoS with hyperons built within the relativistic mean-field (RMF) formalism with baryon-density- and isospin-density-dependent couplings. Motivated by microscopic calculations showing density- and isospin-asymmetry-dependence of self-energies, we implement a new form for the baryon-meson couplings. The parameters for the couplings are constrained by a Bayesian analysis, which anchors the model to nuclear saturation properties, chiral effective field theory ($\chi$EFT) predictions for pure neutron matter, heavy-ion collision data, and HALQCD-based hyperon potential calculations at 3-momentum $|\mathbf{k}|=0$ in both isospin-symmetric and pure neutron matter. The resulting EoS satisfies neutron star mass-radius constraints from NICER and GW170817, providing another way to address the hyperon puzzle. The low-density part of the EoS is described via nuclear statistical equilibrium with modern mass tables (AME20/FRDM12, 8244 nuclei), providing a novel and complete general-purpose EoS for astrophysical simulations.