Isospin-dependent properties of asymmetric nuclear matter in relativistic mean-field models

TL;DR

This paper compares various relativistic mean-field models to study isospin-dependent properties of asymmetric nuclear matter, focusing on symmetry energy, nuclear potentials, and effective mass splitting, and evaluates their consistency with experimental constraints.

Contribution

It provides a comprehensive comparison of different relativistic mean-field models and identifies which parameter sets align with empirical data on symmetry energy and related properties.

Findings

Few parameter sets match empirical symmetry energy constraints.

Symmetry potential and effective mass splitting depend on interaction details and potential definitions.

Models show varying predictions for isospin-dependent properties, highlighting the importance of model selection.

Abstract

Using various relativistic mean-field models, including the nonlinear ones with meson field self-interactions, those with density-dependent meson-nucleon couplings, and the point-coupling models without meson fields, we have studied the isospin-dependent bulk and single-particle properties of asymmetric nuclear matter. In particular, we have determined the density dependence of nuclear symmetry energy from these different relativistic mean-field models and compare the results with the constraints recently extracted from analyses of experimental data on isospin diffusion and isotopic scaling in intermediate-energy heavy ion collisions as well as from measured isotopic dependence of the giant monopole resonances in even-A Sn isotopes. Among the 23 parameter sets in the relativistic mean-filed model that are commonly used for nuclear structure studies, only a few are found to give symmetry energies that are consistent with the empirical constraints. We have also studied the nuclear symmetry potential and the isospin-splitting of the nucleon effective mass in isospin asymmetric nuclear matter. We find that both the momentum dependence of the nuclear symmetry potential at fixed baryon density and the isospin-splitting of the nucleon effective mass in neutron-rich nuclear matter depend not only on the nuclear interactions but also on the definition of the nucleon optical potential.