# Nucleosynthesis in heavy-ion collisions at the LHC via the Saha equation

## TL;DR

This paper applies the Saha equation, traditionally used in cosmology, to model the production of light nuclei in heavy-ion collisions at the LHC, showing that their abundances can be understood through chemical equilibrium without exponential temperature dependence.

## Contribution

It introduces a novel application of the Saha equation to heavy-ion collision nucleosynthesis, providing an alternative to thermal models and aligning with experimental data.

## Key findings

- Agreement with ALICE data on light nuclei yields across various temperatures.
- Light nuclei abundances follow a chemical equilibrium pattern rather than exponential thermal dependence.
- Supported by observed resonance suppression in central Pb-Pb collisions.

## Abstract

The production of light (anti-)(hyper-)nuclei in heavy-ion collisions at the LHC is considered in the framework of the Saha equation, making use of the analogy between the evolution of the early universe after the Big Bang and that of "Little Bangs" created in the lab. Assuming that disintegration and regeneration reactions involving light nuclei proceed in relative chemical equilibrium after the chemical freeze-out of hadrons, their abundances are determined through the famous cosmological Saha equation of primordial nucleosynthesis and show no exponential dependence on the temperature typical for the thermal model. A quantitative analysis, performed using the hadron resonance gas model in partial chemical equilibrium, shows agreement with experimental data of the ALICE collaboration on d, $^3$He, $^3_\Lambda$H, and $^4$He yields for a very broad range of temperatures at $T \lesssim 155$ MeV. The presented picture is supported by the observed suppression of resonance yields in central Pb-Pb collisions at the LHC.