Effects of isospin and momentum dependent interactions on thermal properties of asymmetric nuclear matter

TL;DR

This study investigates how isospin and momentum-dependent interactions influence the thermal properties, phase transitions, and instabilities of asymmetric nuclear matter, revealing that temperature affects symmetry energy and single-particle potentials.

Contribution

It introduces a comprehensive thermal model incorporating isospin and momentum-dependent interactions constrained by experimental data, analyzing their effects on nuclear matter properties and phase behavior.

Findings

Symmetry energy decreases with temperature, mainly due to potential contributions.

Low momentum nucleon properties increase significantly with temperature.

Instability boundaries shrink as temperature rises, sensitive to symmetry energy and interaction details.

Abstract

Thermal properties of asymmetric nuclear matter are studied within a self-consistent thermal model using an isospin and momentum dependent interaction (MDI) constrained by the isospin diffusion data in heavy-ion collisions, a momentum-independent interaction (MID), and an isoscalar momentum-dependent interaction (eMDYI). In particular, we study the temperature dependence of the isospin-dependent bulk and single-particle properties, the mechanical and chemical instabilities, and liquid-gas phase transition in hot asymmetric nuclear matter. Our results indicate that the temperature dependence of the equation of state and the symmetry energy are not so sensitive to the momentum dependence of the interaction. The symmetry energy at fixed density is found to generally decrease with temperature and for the MDI interaction the decrement is essentially due to the potential part. It is further shown that only the low momentum part of the single-particle potential and the nucleon effective mass increases significantly with temperature for the momentum-dependent interactions. For the MDI interaction, the low momentum part of the symmetry potential is significantly reduced with increasing temperature. For the mechanical and chemical instabilities as well as the liquid-gas phase transition in hot asymmetric nuclear matter, our results indicate that the boundary of these instabilities and the phase-coexistence region generally shrink with increasing temperature and is sensitive to the density dependence of the symmetry energy and the isospin and momentum dependence of the nuclear interaction, especially at higher temperatures.