Systematic study of scalar, vector, and mixed density dependencies in relativistic mean-field descriptions of hyperonic matter in neutron stars

TL;DR

This study systematically examines how different density dependencies in meson-baryon couplings affect the equation of state of hyperonic neutron star matter within a relativistic mean-field framework, with implications for neutron star properties.

Contribution

It introduces and compares new density-dependent parameterizations in the relativistic mean-field model for hyperonic matter, exploring their impact on neutron star equations of state and observable properties.

Findings

Most new parameterizations produce stiffer EOSs.

Stiffer EOSs lead to larger neutron star radii and higher tidal deformabilities.

Inclusion of hyperons softens the EOS but still satisfies mass constraints.

Abstract

We investigate the equation of state (EOS) of hyperonic neutron star (NS) matter within a density-dependent relativistic mean-field (DDRMF) framework. The effects of scalar, vector, and mixed density dependencies in meson-baryon couplings are systematically examined along with alternative forms of the $\rho$-meson coupling. Several meson-nucleon parameter sets are explored here for the first time for neutron stars and compared with the standard DD2 EOS. Most new parameterizations produce stiffer EOSs, leading to neutron stars with larger radii and higher tidal deformabilities. However, the inclusion of $\Lambda$ hyperons softens these EOSs, and the resulting maximum masses still satisfy the two solar mass limits and agree with NICER measurements. These results highlight the importance of exploring alternative density dependencies in constraining dense matter through multi-messenger observations.