Delta isobars in relativistic mean-field models with $\sigma$-scaled hadron masses and couplings

TL;DR

This paper extends relativistic mean-field models to include $Delta(1232)$ baryons, analyzing empirical data to constrain their couplings and demonstrating that the resulting equations of state satisfy key astrophysical and nuclear constraints.

Contribution

It introduces $Delta$ baryons into scalar-field-dependent relativistic mean-field models and assesses their impact on neutron star and nuclear matter properties.

Findings

Equations of state with $Delta$s meet empirical constraints

Constraints on $Delta$-meson couplings derived from data

Models remain consistent with neutron star mass and heavy-ion collision observations

Abstract

We extend the relativistic mean-field models with hadron masses and meson-baryon coupling constants dependent on the scalar $\sigma$ field, studied previously to incorporate $\Delta(1232)$ baryons. Available empirical information is analyzed to put constraints on the couplings of $\Delta$s with meson fields. Conditions for the appearance of $\Delta$s are studied. We demonstrate that with inclusion of the $\Delta$s our equations of state continue to fulfill majority of known empirical constraints including the pressure-density constraint from heavy-ion collisions, the constraint on the maximum mass of the neutron stars, the direct Urca and the gravitational-baryon mass ratio constraints.