Quark spectrum above but near critical temperature of chiral transition

Abstract

We explore the quark properties at finite temperature near but above the critical temperature of the chiral phase transition. We investigate the effects of the precursory soft mode of the phase transition on the quark dispersion relation and the spectral function. It is found that there appear novel excitation spectra of quasi-quarks and quasi-antiquarks with a three-peak structure, which are not attributed to the hard-thermal-loop approximation. We show that the new spectra originate from the mixing between a quark (anti-quark) and an anti-quark hole (quark hole) caused by a "resonant scattering" of the quasi-fermions with the thermally-excited soft mode which has a small but finite excitation energy.

Collective Perspective on Advances in Dyson—Schwinger Equation QCD

“…Furthermore, given the qualitative differences between Refs. [304,306] and Ref. [29], the similarity between results suggests the possibility that the appearance of zero modes is model-independent.…”

“…Whilst Refs. [304,306] extract spectral densities via oneloop estimates in Nambu-Jona-Lasinio-or Yukawa-like models, the couplings are tuned to mimic a world in which chiral symmetry is dynamically broken. In this connection we re-emphasise that the zero mode appears only when the strength of the interaction is capable of producing DCSB in-vacuum; viz., when the gap equation's T = 0 kernel has sufficient support at infrared momenta.…”

Quark Spectrum Above the Critical Temperature From Schwinger–dyson Equation

“…In Ref. 9, it is shown that the quark spectrum near T c of the chiral phase transition has three peaks through a coupling with fluctuations of the chiral condensate.…”

Chiral transition and mesonic excitations for quarks with thermal masses

“…(1) in this work, the quark spectrum near T c may have the large decay width and a complicated dispersion [10,15]. It is interesting to explore mesonic excitations with such quark spectra instead of S HTL mT .…”