Signatures of fireball fragmentation at the phase transition

TL;DR

This paper discusses how fireballs formed in ultrarelativistic nuclear collisions can fragment during phase transitions, affecting observable particle distributions and correlations.

Contribution

It introduces the concept that fireball fragmentation can occur at both first-order and crossover phase transitions, and reviews potential experimental observables.

Findings

Fragmentation can occur at first-order phase transitions.

Event-by-event rapidity distribution changes indicate fragmentation.

Proton correlations in rapidity can signal fragmentation.

Abstract

It is explained why and how the fireball created in ultrarelativistic nuclear collisions can fragment when passing the phase transition. It can happen at the first-order phase transition but is not excluded even at high collision energies where the smooth crossover is present. Two potential observables sensitive to the appearance of fragmentation are reviewed: event-by-event changes of rapidity distributions and proton correlation in relative rapidity.