Thermal properties of asymmetric nuclear matter with an improved isospin- and momentum-dependent interaction

TL;DR

This study explores how the thermal properties of asymmetric nuclear matter, including symmetry energy and isospin fractionation, are influenced by effective mass splitting using an improved interaction model fitted to experimental data.

Contribution

The paper introduces an improved isospin- and momentum-dependent interaction model with adjustable parameters, providing a flexible framework to study thermal properties of nuclear matter.

Findings

Effective mass splitting impacts phase-space distribution.

Temperature affects symmetry energy significantly.

Isospin fractionation is sensitive to effective mass differences.

Abstract

Thermal properties of asymmetric nuclear matter, including the temperature dependence of the symmetry energy, single-particle properties, and differential isospin fractionation, are investigated with different neutron-proton effective mass splittings using an improved isospin- and momentum-dependent interaction. In this improved interaction, the momentum-dependence of the isoscalar single-particle potential at saturation density is well fitted to that extracted from optical model analyses of proton-nucleus scattering data up to nucleon kinetic energy of 1 GeV, and the isovector properties, i.e., the slope of the nuclear symmetry energy, the momentum-dependence of the symmetry potential, and the symmetry energy at saturation density can be flexibly adjusted via three parameters $x$, $y$, and $z$, respectively. Our results indicate that the nucleon phase-space distribution in equilibrium, the temperature dependence of the symmetry energy, and the differential isospin fractionation can be significantly affected by the isospin splitting of nucleon effective mass.