Low-density in-medium effects on light clusters from heavy-ion data

TL;DR

This paper investigates how light nuclei properties are altered in nuclear and stellar environments using heavy-ion collision data, revealing the necessity of in-medium corrections for accurate interpretation.

Contribution

It introduces a new analysis method for chemical equilibrium constants from heavy-ion data, accounting for in-medium effects on light clusters.

Findings

In-medium effects are essential for accurate chemical constant analysis.

Data aligns with a relativistic mean-field model with a universal sigma-meson correction.

Strong deviations from ideal gas behavior are observed in the data.

Abstract

The modification of the ground state properties of light atomic nuclei in the nuclear and stellar medium is addressed, using chemical equilibrium constants evaluated from a new analysis of the intermediate energy heavy-ion (Xe$+$Sn) collision data measured by the INDRA collaboration. Three different reactions are considered, mainly differing by the isotopic content of the emission source. The thermodynamic conditions of the data samples are extracted from the measured multiplicities allowing for a parametrization of the in-medium modification, determined with the single hypothesis that the different nuclear species in a given sample correspond to a unique common value for the density of the expanding source. We show that this correction, which was not considered in previous analyses of chemical constants from heavy ion collisions, is necessary, since the observables of the analyzed systems show strong deviations from the expected results for an ideal gas of free clusters. This data set is further compared to a relativistic mean-field model, and seen to be reasonably compatible with a universal correction of the attractive $\sigma$-meson coupling.