QCD phase transition studied by means of hadron production

TL;DR

This paper reviews the hadronization process of a quark-gluon plasma in heavy-ion collisions, introducing the SHARE analysis method and revealing a universal hadronization pressure across different collision energies.

Contribution

It introduces the SHARE method for analyzing hadron multiplicities and demonstrates a universal hadronization pressure in QGP fireballs across SPS, RHIC, and LHC.

Findings

Universal hadronization pressure of 80 MeV/fm^3

Consistent description of hadron yields across energies

Strangeness to entropy ratio indicates QGP degrees of freedom

Abstract

This is a brief review of our work describing the hadronization process of a QGP fireball formed in relativistic heavy-ion collisions. We introduce the SHARE method of analysis of hadron multiplicities. Using this tool we describe in consistent continuos manner the yield of all hadrons produced in the available range of reaction energies and centralities. The properties of the fireball final state can be understood by considering all primary hadronic particles. The dense hadron fireball created at SPS, RHIC, and LHC shows that the final state is differentiated solely by: i) volume changes; and ii) flavor (strangeness, charm) content. Conversely, emerging particles add up to create universal hadronization pressure $P = 80 \pm 3$ MeV/fm$^3$ for all considered collision systems. The relative strangeness to entropy content of a large fireball is found to be that of quark-gluon plasma degrees of freedom near the chemical QGP equilibrium. This 'Universal Hadronization' condition common to SPS, RHIC, and LHC agrees with the proposed reaction picture of a direct QGP fireball evaporation into free-streaming hadrons.