Formation of light nuclei at chemical freezeout: Description within a statistical thermal model

TL;DR

This paper investigates the formation of light nuclei at chemical freezeout using a thermal model, introducing a new method based on phase space density proximity, and finds that nuclei form near freezeout before hadronic decay.

Contribution

A novel approach to study light nuclei formation by comparing phase space densities of nuclei and their constituents within a thermal model.

Findings

Good agreement between hadronic yields and light nuclei ratios when decay feed-down is excluded.

Nuclei and hypernuclei likely form near the chemical freezeout point.

The method provides a guideline for including decay processes in light nuclei formation studies.

Abstract

The thermal description of light nuclei at the chemical freeze-out has been investigated. First, I have verified the equilibration of the light nuclei and then introduced a new method to investigate the light nuclei formation. One can study the proximity between the phase space density of light nuclei ratios and their hadronic constituents e.g $\bar{d}/d$ and $(\bar{p}\bar{n}/pn)$. I have found that with the exclusion of the decay feed-down from the hadronic yields in the thermal model, the hadronic representations have good agreement with the light nuclei ratios. I have performed a similar analysis with the ratio of $\Lambda$-hypernuclei and $^3 He$, which is related to the ratio $\Lambda/p$. In this context, the strangeness population factor $S_3$ has been studied also. These results indicate that the nuclei and hypernuclei formation may occur near the standard chemical freeze-out and before the decay of the hadronic resonances. This method will serve as a guideline to discuss the light nuclei formation and the inclusion of decay into their hadronic constituents.