Enhanced Dilepton production near the color superconducting phase and the QCD critical point

TL;DR

This study investigates dilepton production in heavy ion collisions near the QCD critical point and color superconducting phase, revealing characteristic enhancements and structures that could signal these phases and depend on the diquark coupling.

Contribution

It introduces a detailed analysis of dilepton yields near the QCD critical point and CSC phase using the NJL model, highlighting potential experimental signatures.

Findings

Enhanced ultra-low energy dilepton yield near the CSC phase and QCD-CP

Distinctive nontrivial energy dependence patterns of dilepton yield

Dependence of yield features on diquark coupling strength

Abstract

The dilepton production yields in relativistic heavy ion collisions are investigated along isentropic trajectories in the quark (Wigner) phase within the two-flavor Nambu-Jona-Lasinio model. An enhancement of the ultra-low energy dilepton yield in the vicinity of the color superconducting (CSC) phase and the QCD critical point (QCD-CP) is found, compared to the free quark gas. Furthermore, we have found a nontrivial structure in the beam energy dependence of the ultra-low energy dilepton yield. A local maximum and minimum of the dilepton yield as a function of entropy per baryon emerge when the trajectories are close to both locations of the CSC phase transition line and the QCD-CP. Only the maximum appears in the scenario without the CSC phase but with the QCD-CP. On the other hand, when only the CSC phase is considered, the dilepton yield monotonically increases as the beam energy decreases. These distinctive patterns could potentially serve as signals of the CSC phase and QCD-CP. In addition, it is found that the dilepton production yield and the location of the minimum strongly depend on the value of diquark coupling, suggesting the possibility that the value of the diquark coupling may be extracted from experimental data.