In-medium reduction of the \eta' mass in \sqrt{s_NN} = 200 GeV Au+Au collisions

TL;DR

This study investigates the in-medium mass reduction of the ta' meson in high-energy Au+Au collisions, suggesting a possible restoration of UA(1) symmetry in hot, dense matter through analysis of pion correlation data.

Contribution

It provides evidence for a significant ta' mass reduction in heavy-ion collisions, indicating symmetry restoration, based on combined PHENIX and STAR experimental data.

Findings

ta' mass reduced by at least 200 MeV at 99.9% confidence

Energy and system size dependence observed

Supports ta' mass modification in hot dense matter

Abstract

A reduction of the mass of the \eta'(958) meson may indicate the restoration of the UA(1) symmetry in a hot and dense hadronic matter, corresponding to the return of the 9th, "prodigal" Goldstone boson. We report on an analysis of a combined PHENIX and STAR data set on the intercept parameter of the two-pion Bose-Einstein correlation functions, as measuremed in \sqrt{s_NN} = 200 GeV Au+Au collisions at RHIC. To describe this combined PHENIX and STAR dataset, an in-medium \eta' mass reduction of at least 200 MeV is needed, at the 99.9 % confidence level in a broad model class of resonance multiplicities. Energy, system size and centrality dependence of the observed effect is also discussed.