The Quark Propagator in the NJL Model in a self-consistent 1/Nc Expansion

Abstract

The quark propagator is calculated in the Nambu-Jona-Lasinio (NJL) model in a self-consistent 1/Nc-expansion at next-to-leading order. The calculations are carried out iteratively in Euclidean space. The chiral quark condensate and its dependence on temperature and chemical potential is calculated directly and compared with the mean-field results. In the chiral limit, we find a second-order phase transition at finite temperature and zero chemical potential, in agreement with universality arguments. At zero temperature and finite chemical potential, the phase transition is first order. In comparison with the mean-field results, the critical temperature and chemical potential are slightly reduced. We determine spectral functions from the Euclidean propagators by employing the Maximum-Entropy-Method (MEM). Thereby quark and meson masses are estimated and decay channels identified. For testing this method, we also apply it to evaluate perturbative spectral functions, which can be calculated directly in Minkowski space. In most cases we find that MEM is able to reproduce the rough features of the spectral functions, but not the details.

14 pages, 19 figures

References in corpus (3)

• Susceptibilities near the QCD (tri)critical point
• Effects of mesonic correlations in the QCD phase transition
• Extraction of Spectral Functions from Dyson-Schwinger Studies via the Maximum Entropy Method

Cited by in corpus (7)

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• The nuclear liquid-gas phase transition at large $N_c$ in the Van der Waals approximation
• Shear Viscosity and Phase Diagram from Polyakov$-$Nambu$-$Jona-Lasinio model
• Chiral restoration at finite T under the magnetic field with the meson-loop corrections
• Effect of mesonic off-shell correlations in the PNJL equation of state
• Chiral restoration at finite temperature with meson loop corrections
• Gauge invariant spectral analysis of quark hadronization dynamics