# On separate chemical freeze-outs of hadrons and light (anti)nuclei in high energy nuclear collisions

## TL;DR

This paper investigates the chemical freeze-out conditions of hadrons and light (anti)nuclei in high-energy nuclear collisions using an advanced hadron resonance gas model with induced surface tension, revealing different freeze-out temperatures for these particles.

## Contribution

It introduces a model incorporating a simple radius law for nuclei and analyzes ALICE data to distinguish separate freeze-out scenarios for hadrons and (anti)nuclei.

## Key findings

- Hadrons freeze out at approximately 150 MeV.
- (Anti)nuclei freeze out at approximately 168.5 MeV.
- Different freeze-out temperatures suggest separate chemical freeze-out processes.

## Abstract

The multiplicities of light (anti)nuclei were measured recently by the ALICE collaboration in Pb+Pb collisions at the center-of-mass collision energy $\sqrt{s_{NN}} =2.76$ TeV. Surprisingly, the hadron resonance gas model is able to perfectly describe their multiplicities under various assumptions. For instance, one can consider the (anti)nuclei with a vanishing hard-core radius (as the point-like particles) or with the hard-core radius of proton, but the fit quality is the same for these assumptions. In this paper we assume the hard-core radius of nuclei consisting of $A$ baryons or antibaryons to follow the simple law $R(A) = R_b (A)^\frac{1}{3}$, where $R_b$ is the hard-core radius of nucleon. To implement such a relation into the hadron resonance gas model we employ the induced surface tension concept and analyze the hadronic and (anti)nuclei multiplicities measured by the ALICE collaboration. The hadron resonance gas model with the induced surface tension allows us to verify different scenarios of chemical freeze-out of (anti)nuclei. It is shown that the most successful description of hadrons can be achieved at the chemical freeze-out temperature $T_h=150$ MeV, while the one for all (anti)nuclei is $T_A=168.5$ MeV. Possible explanations of this high temperature of (anti)nuclei chemical freeze-out are discussed.