Collective Phenomena in Heavy Ion Collisions

TL;DR

This paper reviews experimental results on collective phenomena in heavy ion collisions across different energy ranges, highlighting how collision parameters influence the properties of hot, dense baryonic matter and the transition to partonic states.

Contribution

It provides a comprehensive comparison of flow analysis results at SIS and high energies, revealing insights into the equation of state and thermalization in heavy ion collisions.

Findings

Mass and centrality affect collective expansion and equation of state.

Transverse momentum analysis indicates thermalization at high energies.

Differences between baryonic and partonic expansion regimes.

Abstract

A review of the main results of detailed flow analysis in highly central and semi-central heavy ion collisions at SIS energies is presented in the first part of this paper. The influence of the mass of the colliding nuclei and centrality on the collective expansion and the information on the equation of state of compressed and hot baryonic matter is discussed. The second part is dedicated to a similar type of analysis, based on the behaviour of the average transverse momentum as a function of mass of different hadrons, at the other extreme of energy range, where free baryonic fireballs are produced. Information on the partonic and hadronic expansion, temperature and degree of thermal equilibrium in p+p and Au+Au central collisions at 200 A.GeV is presented.