Observables of non-equilibrium phase transition

TL;DR

This paper investigates signatures of non-equilibrium first-order phase transitions in heavy-ion collisions, focusing on rapidity correlations, fluctuations, and event sorting methods to identify fragmentation phenomena.

Contribution

It introduces a novel approach to detect fragmentation signatures through rapidity correlations, event-by-event fluctuations, and a new event sorting method based on rapidity histograms.

Findings

Rapidity correlations reveal emission from fragments.

Event-to-event fluctuations indicate fragmentation.

A new event sorting method groups similar rapidity distributions.

Abstract

A rapidly expanding fireball which undergoes first-order phase transition will supercool and proceed via spinodal decomposition. Hadrons are produced from the individual fragments as well as the left-over matter filling the space between them. Emission from fragments should be visible in rapidity correlations, particularly of protons. In addition to that, even within narrow centrality classes, rapidity distributions will be fluctuating from one event to another in case of fragmentation. This can be identified with the help of Kolmogorov-Smirnov test. Finally, we present a method which allows to sort events with varying rapidity distributions in such a way, that events with similar rapidity histograms are grouped together.