Is Strangeness Chemically Equilibrated?

TL;DR

This paper reviews evidence for chemical equilibration of hadrons in heavy ion collisions, examining effects like heavy resonances and deviations from standard statistical models, with strong overall support but notable exceptions.

Contribution

It provides a comprehensive review of chemical equilibration evidence and investigates the impact of heavy resonances and non-standard distributions on this process.

Findings

Strong evidence for chemical equilibration in heavy ion collisions

Deviations observed in multi-strange hadrons

Heavy resonances and Tsallis distribution effects are significant

Abstract

Results related to the possible chemical equilibration of hadrons in heavy ion collisions are reviewed. Overall the evidence is very strong with a few clear and well-documented deviations, especially concerning multi-strange hadrons. Two effects are considered in some detail. Firstly, the neglect of (possibly an infinite number) of heavy resonances is investigated with the help of the Hagedorn model. Secondly, possible deviations from the standard statistical distributions are investigated by considering in detail results obtained using the Tsallis distribution.