Investigating the cluster production mechanism with isospin triggering: Thermal models versus coalescence models

TL;DR

This paper compares thermal and coalescence models for light cluster production in heavy ion collisions, using isospin triggering to distinguish the mechanisms and identify the dominant process based on yield patterns.

Contribution

It introduces isospin triggering as a method to differentiate between coalescence and thermal production of light clusters in heavy ion collisions.

Findings

Deuteron yield shows an inverse parabolic dependence on isospin trigger in coalescence models.

Thermal models predict no dependence of cluster yield on isospin trigger.

Observation of a maximum deuteron yield supports the coalescence mechanism.

Abstract

Isospin triggering allows to distinguish coalescence from thermal production of light clusters in heavy ion collisions. Triggering on $Y(\pi^-) - Y(\pi^+)$ allows to select very neutron or proton rich final states. The deuteron (cluster) production with coalescence ($d \propto n \cdot p$) leads then to an inverse parabolic dependence of the deuteron yield on $\Delta Y_{\pi}$. In contrast, in a thermal model, cluster production is independent on $\Delta Y_{\pi}$. The observation of a maximum deuteron (cluster) yield as function of $\Delta Y_{\pi}$ provides confirmation of the coalescence mechanism.