Search for QCD Phase Transitions and the Critical Point utilizing Particle Ratio Fluctuations and Transverse Momentum Correlations from the STAR Experiment

TL;DR

This paper investigates QCD phase transitions and the critical point by analyzing particle ratio fluctuations and transverse momentum correlations in heavy ion collisions using STAR experiment data across various energies.

Contribution

It provides comprehensive measurements of fluctuation observables and correlations across energies, offering new insights into QCD phase transition signals and comparing results with hadronic models.

Findings

Energy dependence of fluctuation observables shows potential signals of phase transition.

Centrality and charge dependence reveal detailed fluctuation patterns.

Results are consistent or challenge existing hadronic model predictions.

Abstract

Dynamical fluctuations of the globally conserved quantities in heavy ion collision such as baryon number, strangeness, charge, and isospin are suggested to carry information about the deconfinement and chiral phase transitions. The STAR experiment has performed a comprehensive study of the collision energy and charge dependence of dynamical particle ratio ($K/\pi$, $p/\pi$, and $K/p$) fluctuations, net-charge fluctuations, and transverse momentum correlations at mid-rapidity, as well as neutral-charge pion fluctuations at forward rapidity. The centrality, charge, and collision energy dependence from new measurements of the fluctuation observables $\nu_{dyn}$ and $r_{m,1}$ and the energy dependence of transverse momentum correlations from $\sqrt{s_{NN}}$ = 7.7-200 GeV Au+Au collisions are presented. These results are also compared to predictions from hadronic models.