Deuteron Production in Ultra-Relativistic Heavy-Ion Collisions: A Comparison of the Coalescence and the Minimum Spanning Tree Procedure

TL;DR

This study compares two clustering methods, MST and coalescence, for deuteron formation in ultra-relativistic heavy-ion collisions, finding similar results that align well with experimental data and reveal insights into deuteron spatial distributions.

Contribution

The paper introduces a comparative analysis of MST and coalescence models embedded in transport approaches for deuteron production, highlighting their consistency and agreement with experimental results.

Findings

Both methods yield similar deuteron observables.

Results agree with experimental data from Pb+Pb collisions.

Deuterons have distinct spatial distributions, unaffected by rescattering.

Abstract

The formation of deuterons in heavy-ion collisions at relativistic energies is investigated by employing two recently advanced models -- the Minimum Spanning Tree (MST) method and the coalescence model by embedding them in the PHQMD and the UrQMD transport approaches. While the coalescence mechanism combines nucleons into deuterons at the kinetic freeze-out hypersurface, the MST identifies the clusters during the different stages of time evolution. We find that both clustering procedures give very similar results for the deuteron observables in the UrQMD as well as in the PHQMD environment. Moreover, the results agree well with the experimental data on deuteron production in Pb+Pb collisions at $\sqrt{s_{NN}} = 8.8$ GeV (selected for the comparison of the methods and models in this study). A detailed investigation shows that the coordinate space distribution of the produced deuterons differs from that of the free nucleons and other hadrons. Thus, deuterons are not destroyed by additional rescattering.