Radial Flow from Electromagnetic Probes and Signal of Quark Gluon Plasma

TL;DR

This paper analyzes electromagnetic probe data from SPS and RHIC to extract radial flow evolution, suggesting it indicates a phase transition from partons to hadrons in quark-gluon plasma formation.

Contribution

It presents a novel method to extract radial flow evolution from electromagnetic probes, providing largely model-independent evidence of phase transition signals.

Findings

Radial velocity varies with invariant mass.

Evidence supports phase transition from partons to hadrons.

Analysis is largely model independent.

Abstract

A first attempt has been made to extract the evolution of radial flow from the analysis of the experimental data on electromagnetic probes experimentally measured at SPS and RHIC energies. The $p_T$ spectra of photons and dileptons measured by WA98 and NA60 collaborations respectively at CERN-SPS and the photon spectra obtained by PHENIX collaboration at BNL-RHIC have been used to constrain the theoretical models, rendering the outcome of the analysis largely model independent. We argue that the variation of the radial velocity with invariant mass is indicative of a phase transition from initially produced partons to hadrons at SPS and RHIC energies.