Exploring the QCD phase diagram via the collision energy dependence of multi-particle femtoscopy with PHENIX

TL;DR

This study investigates the QCD phase diagram by analyzing multi-particle femtoscopy in heavy ion collisions across various energies, focusing on Bose-Einstein correlations to locate the critical endpoint.

Contribution

It introduces a comprehensive measurement of Bose-Einstein correlations using Levy-type source functions across multiple collision energies, extending analysis from two- to three-particle correlations.

Findings

Measured the energy and centrality dependence of the Levy alpha parameter.

Confirmed the consistency of two- and three-particle correlation results.

Provided insights into pion production mechanisms beyond the core-halo model.

Abstract

Exploration of the rich structure of the QCD phase diagram is an important topic in the RHIC heavy ion program. One of the ultimate goals of this program is to search for the critical endpoint. Investigation of the space-time structure of hadron emissions at various phase transition points using Bose-Einstein correlations of identical bosons may provide insight on the location of the critical endpoint. PHENIX has performed comprehensive measurements of the Bose-Einstein correlation in Au+Au collisions at sqrt(sNN) = 15, 19, 27, 39, 62.4, and 200 GeV, where we incorporated Levy-type source functions to describe the measured correlation functions. We put particular focus on one of the parameters of the Levy-type source functions, the index of stability alpha, which is related to one of the critical exponents (the so-called correlation exponent eta). We have measured its collision energy and centrality dependence. We have also extended our analysis from two-particle to three-particle correlations to characterize the nature of the hadron emission source. The three particle correlations confirmed the findings of the two-particle correlations, and also provide insight on the pion production mechanism beyond the core-halo model.