Composition and thermodynamics of nuclear matter with light clusters

TLDR

Nucleons and clusters are modified by medium effects. The study investigates nuclear matter at finite temperature and density, focusing on light cluster formation and dissolution, using quantum statistical and relativistic mean‑field approaches. Cluster dissociation is modeled via the Mott effect from Pauli blocking, implemented differently in QS and RMF; the authors compare numerical results for cluster abundances and thermodynamics across temperatures up to 20 MeV and densities up to a few times saturation, examining effects on the liquid‑gas phase transition and symmetry energy, and benchmark against other astrophysical models. Both approaches reproduce the limiting cases of nuclear statistical equilibrium at low densities and cluster‑free nuclear matter at high densities, making the results relevant for heavy‑ion collisions and astrophysical applications.

Abstract

We investigate nuclear matter at finite temperature and density, including the formation of light clusters up to the alpha particle The novel feature of this work is to include the formation of clusters as well as their dissolution due to medium effects in a systematic way using two many-body theories: a microscopic quantum statistical (QS) approach and a generalized relativistic mean field (RMF) model. Nucleons and clusters are modified by medium effects. Both approaches reproduce the limiting cases of nuclear statistical equilibrium (NSE) at low densities and cluster-free nuclear matter at high densities. The treatment of the cluster dissociation is based on the Mott effect due to Pauli blocking, implemented in slightly different ways in the QS and the generalized RMF approaches. We compare the numerical results of these models for cluster abundances and thermodynamics in the region of medium excitation energies with temperatures T <= 20 MeV and baryon number densities from zero to a few times saturation density. The effect of cluster formation on the liquid-gas phase transition and on the density dependence of the symmetry energy is studied. Comparison is made with other theoretical approaches, in particular those, which are commonly used in astrophysical calculations. The results are relevant for heavy-ion collisions and astrophysical applications.