Emergence of soft quark excitations by the coupling with a soft mode of the QCD critical point

TL;DR

This paper investigates how soft modes near the QCD critical point affect quark excitations, revealing significant spectral shifts and the influence of pions, within a chiral effective model at finite temperature and density.

Contribution

It demonstrates the impact of scalar- and pseudoscalar-density fluctuations on quark spectra near the QCD critical point, highlighting the role of soft modes in spectral modifications.

Findings

Soft modes cause a shift in the quasiquark peak near the critical point.

Scalar-density fluctuations significantly influence the quark spectrum.

Pions also affect the quark spectral properties near the critical point.

Abstract

We study the quark spectrum at nonzero temperature and density near the critical point (CP) of the chiral phase transition incorporating effects of the scalar- and pseudoscalar-density fluctuations in a chiral effective model with a nonzero current quark mass. It is known that the soft mode associated with the second-order transition at the CP lies in the spacelike region of the scalar-density fluctuation. We find that the soft mode influences the quark spectrum significantly near the CP, resulting in the shift of the quasiquark peak. Effects of the composite stable pions on the quark spectrum near the CP are also discussed.