Dilepton Production as a Probe of Pion Condensation in Hot and Dense QCD Matter

TL;DR

This paper explores how pion condensation in hot, dense, isospin-asymmetric QCD matter affects dilepton production rates, revealing distinctive spectral features that could signal the condensed phase in experiments.

Contribution

It models the dilepton production rate in pion condensed phases using the NJL model, identifying spectral signatures of pion condensation in hot and dense environments.

Findings

Enhanced dilepton yield at lower invariant mass in pion condensed phase

Plateau-like structure in dilepton spectrum indicating pion condensation

Potential experimental signatures for identifying pion condensed phase

Abstract

We investigate dilepton production from an isospin-asymmetric hot and dense medium in order to explore the role of isospin imbalance in electromagnetic spectral properties. We focus in particular on modifications of the dilepton production rate associated with the onset of pion condensation, which can occur in the presence of a finite isospin chemical potential. We employ the Nambu--Jona-Lasinio model with isoscalar--vector interaction. We examine the phase structure in the $T-\mu_I$ plane and estimate the vector current correlator--resummed dilepton rate for an effective quark chemical potential. We find that the interplay between isospin asymmetry, pion condensation, and vector interactions leads to nontrivial modifications of the dilepton yield. In particular, we observe two key features of the pion condensed phase: an enhancement at lower invariant mass and a prominent plateau-like structure which also help clearly identify the pion condensed phase from a chirally broken/restored phase. These results highlight the potential sensitivity of dilepton observables to pion-condensed phase of QCD matter, with possible implications for future low-energy heavy-ion collision experiments as well as isospin-rich environments such as neutron star matter.