Measuring radial flow of partonic and hadronic phases in relativistic heavy ion collision

TL;DR

This paper investigates the radial flow in different phases of matter created in ultra-relativistic heavy ion collisions using electromagnetic probes, revealing non-monotonic flow behavior linked to phase transition dynamics.

Contribution

It introduces a method to estimate radial velocities of partonic and hadronic phases via thermal photon and dilepton spectra, highlighting their potential to probe phase transition characteristics.

Findings

Non-monotonic variation of flow velocity with dilepton invariant mass.

Evidence of two distinct thermal dilepton sources at different evolution stages.

Electromagnetic probes can provide insights into the hadron-QGP phase transition.

Abstract

It has been shown that the thermal photon and the lepton pair spectra can be used to estimate the radial velocity of different phases of the matter formed in nuclear collisions at ultra-relativistic energies. We observe a non-monotonic variation of the flow velocity with invariant mass of the lepton pair which is indicative of two different sources of thermal dilepton sources at early and late stage of the dynamically evolving system. We also show that the study of radial velocity through electromagnetic probes may shed light on the nature of the phase transition from hadrons to QGP.