Probing collision dynamics at RHIC

TL;DR

This paper investigates collision dynamics at RHIC by analyzing hadron production in pp and Au+Au collisions, revealing consistent chemical freeze-out temperatures across centralities and insights into the evolution toward kinetic freeze-out.

Contribution

It provides new measurements and analysis of chemical and kinetic freeze-out parameters in heavy-ion collisions at RHIC, enhancing understanding of collision evolution.

Findings

Au+Au collisions reach a universal chemical freeze-out temperature

The system cools and expands from chemical to kinetic freeze-out

Results support models of thermal and chemical equilibrium in collisions

Abstract

Measurements of a variety of hadron species in pp and Au+Au collisions at 200 GeV are presented and studied within the framework of chemical and local kinetic equilibrium models. The extracted chemical and final kinetic freeze-out temperatures and collective flow velocities are discussed as function of centrality. The results suggest that Au+Au collisions of various centralities at RHIC always evolve toward the same temperature at chemical freeze-out, followed by cooling and expansion toward kinetic freeze-out.