Effects of chain decays, radial flow and $U_{A}(1)$ restoration on the low-mass dilepton enhancement in $\sqrt{s_{NN}}=200$ GeV Au+Au reactions

TL;DR

This paper investigates the low-mass dilepton enhancement in high-energy Au+Au collisions, attributing it to in-medium eta' mass reduction, chain decays, and radial flow effects, providing a comprehensive theoretical explanation.

Contribution

It offers a novel combined model incorporating eta' mass reduction, chain decays, and radial flow to explain the dilepton enhancement observed in experiments.

Findings

Successful description of PHENIX dilepton enhancement

Evidence supporting eta' mass reduction in hot medium

Role of chain decays and radial flow in dilepton spectra

Abstract

In sqrt(sNN) = 200 GeV Au+Au collisions PHENIX reported a significant enhancement in the low-mass region (0.1 < m_ee < 0.7 GeV) of the dielectron spectrum, which is still not fully understood. Several theoretical works and an indirect measurement suggest that, due to the possible restoration of the U_A(1) part of the chiral symmetry in a hot and dense medium, the mass of the eta' meson may substantially decrease. This work reports on a statistically acceptable description of the PHENIX low-mass dilepton enhancement using a radial flow dominated meson spectra, chain decays of long-lived resonances and an in-medium eta' mass modification.