Nuclear condensation and symmetry energy of dilute nuclear matter: an S-matrix approach

TL;DR

This paper uses the S-matrix approach to analyze the symmetry energy, free energy, and entropy of dilute nuclear matter, revealing deviations from linear models especially at low temperatures and higher densities.

Contribution

It introduces an S-matrix based method to study clusterized nuclear matter, showing deviations from traditional linear symmetry energy models at certain conditions.

Findings

Symmetry energy deviates from linear dependence at low temperatures.

Symmetry coefficients can be negative in clusterized nuclear matter.

Symmetry entropy exhibits distinct behavior from homogeneous matter.

Abstract

Based on the general analysis of the grand canonical partition function in the S-matrix framework, the calculated results on symmetry energy, free energy and entropy of dilute warm nuclear matter are presented. At a given temperature and density, the symmetry energy or symmetry free energy of the clusterized nuclear matter in the S-matrix formulation deviates, particularly at low temperature and relatively higher density, in a subtle way, from the linear dependence on the square of the isospin asymmetry parameter $X=(\rho_n-\rho_p)/(\rho_n+\rho_p)$, contrary to those obtained for homogeneous nucleonic matter. The symmetry coefficients, in the conventional definition, can then be even negative. The symmetry entropy similarly shows a very different behavior.