Effects of density-dependent scenarios of in-medium nucleon-nucleon interactions in heavy-ion collisions

TL;DR

This study investigates how different density-dependent models of in-medium nucleon-nucleon interactions influence isospin-sensitive observables in heavy-ion collisions, highlighting the importance of considering separate density dependencies for accurate symmetry energy probing.

Contribution

It introduces and compares a separate density-dependent scenario with the traditional total density-dependent scenario for in-medium nucleon-nucleon interactions, revealing their impact on observables.

Findings

Different density-dependent scenarios produce significantly different symmetry potentials at high densities.

Isospin-sensitive observables are notably affected by the choice of density-dependent scenario.

The separate density-dependent scenario should be considered in high-density symmetry energy studies.

Abstract

Using a more reasonable separate density-dependent scenario instead of the total density-dependent scenario for in-medium $nn$, $pp$ and $np$ interactions, we examine effects of differences of in-medium nucleon-nucleon interactions in two density-dependent scenarios on isospin-sensitive observables in central $^{197}$Au+$^{197}$Au collisions at 400 MeV/nucleon. Moreover, to more physically detect the differences between the nucleon-nucleon interactions in two density-dependent scenarios, we also map the nucleon-nucleon interaction in the separate density-dependent scenario into that in the total density-dependent scenario through fitting the identical constraints for symmetric nuclear matter as well as the identical slope parameter of nuclear symmetry energy at the saturation density. It is shown that two density-dependent scenarios also lead to essentially different symmetry potentials especially at high densities although they can lead to the identical equation of state for the symmetry nuclear matter as well as the identical symmetry energy for the isospin asymmetric nuclear matter. Consequently, these isospin-sensitive observables are also appreciably affected by the different density-dependent scenarios of in-medium nucleon-nucleon interactions. Therefore, according to these findings, it is suggested that effects of the separate density-dependent scenario of in-medium nucleon-nucleon interactions should be taken into account when probing the high-density symmetry energy using these isospin-sensitive observables in heavy-ion collisions.