$\eta$ mesons in hot and dense asymmetric nuclear matter

TL;DR

This paper investigates how $ ext{eta}$ mesons behave in hot, dense, and asymmetric nuclear matter using two theoretical approaches, revealing significant in-medium mass shifts influenced by density, temperature, asymmetry, and scattering length.

Contribution

It compares two different theoretical models for $ ext{eta}$ meson interactions in nuclear matter, highlighting differences in predicted mass shifts and the effects of various nuclear conditions.

Findings

Larger negative mass-shift observed in the ChPT+chiral model approach.

Mass-shift decreases with increasing asymmetry and temperature.

Increased $ ext{eta N}$ scattering length leads to greater decrease in $ ext{eta}$ meson mass.

Abstract

We study the $\eta N$ interactions in the hot and dense isospin asymmetric nuclear matter using two different approaches. In the first approach, the in-medium mass and optical potential of $\eta$-meson have been calculated in the chiral SU(3) model, considering the effect of explicit symmetry breaking term and range terms in the $\eta N$ interaction Lagrangian density. In the second scenario, the conjunction of chiral perturbation theory and chiral SU(3) model is employed. In this case, the next-to-leading order $\eta N$ interactions are evaluated from the chiral perturbation theory (ChPT), and the in-medium contribution of scalar densities are taken as input from chiral SU(3) model. We observe a larger negative mass-shift in the ChPT+chiral model approach compared to the chiral SU(3) model alone as a function of nuclear density. Moreover, the increase in the asymmetry and temperature cause a decrease in the magnitude of mass-shift. We have also studied the impact of $\eta N$ scattering length $a^{\eta N}$ on the $\eta$ meson mass $m^*_\eta$ and observed that the $m^*_\eta$ decrease more for increasing the value of scattering length.