Enhancement of dilepton production rate and electric conductivity around QCD critical point

TL;DR

This paper explores how the soft mode at the QCD critical point enhances dilepton production and electric conductivity, potentially observable in heavy-ion collision experiments.

Contribution

It demonstrates that coupling photons with the soft mode at the QCD critical point enhances dilepton production and conductivity, extending previous methods from color-superconducting phases.

Findings

Enhanced dilepton production rate near the QCD critical point.

Increased electric conductivity around the critical point.

Potential observability in relativistic heavy-ion collisions.

Abstract

We investigate whether the soft mode that becomes massless at the QCD critical point (CP) causes an enhancement of the dilepton production rate (DPR) and the electric conductivity around the CP through the modification of the photon self-energy. The modification is described by the so-called Aslamazov-Larkin, Maki-Thompson and density of states terms, which have been taken into account in our previous study on the DPR near the color-superconducting phase transition, with a replacement of the diquark modes with the soft mode of the QCD CP. We show that the coupling of photons with the soft modes brings about an enhancement of the DPR in the low invariant-mass region and the conductivity near the CP, which would be observable in the relativistic heavy-ion collisions.