Medium effects on light clusters from heavy-ion collisions within a relativistic mean-field description

TL;DR

This study uses Bayesian inference within a relativistic mean-field model to analyze heavy-ion collision data, successfully describing light nuclei abundances and exploring in-medium effects, with implications for nuclear matter properties.

Contribution

It introduces a Bayesian approach to estimate thermodynamical parameters and in-medium modifications in heavy-ion collisions, comparing two models of in-medium effects.

Findings

Excellent agreement with experimental light isotope abundances.

In-medium effects cannot be distinguished by current data.

Temperature-dependent meson couplings lead to faster cluster weakening.

Abstract

Central $^{136,124}$Xe$+^{124,112}$Sn collisions from INDRA data are analysed using a Bayesian inference on light nuclei multiplicities to estimate the thermodynamical parameters and in-medium modification of the cluster self-energies within a relativistic mean-field model. An excellent description of experimentally measured abundances of H and He isotopes is obtained. We examine two possible modelling of in-medium effects as an increased in-medium effective mass, or an increased vector repulsion. We show that these physical pictures cannot be discriminated by the data. In both cases, the temperature dependence of the meson couplings leads to a faster weakening of the light cluster abundances with temperature than previous studies predicted. Possible systematic errors due to out-of-equilibrium effects affecting the experimental abundances, are considered by repeating the Bayesian inference with reduced information. The abundance prediction of the species excluded from the constraint is well compatible with the experimental data, suggesting that there is no a priori need of accounting for non-equilibrium effects or finite state interactions that potentially affect the deuteron yield.