Eur. Phys. J. C 70, 1037-1049 (2010)
https://doi.org/10.1140/epjc/s10052-010-1499-8

Quark spectral properties above T _c from Dyson–Schwinger equations

¹ Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 9, 64289, Darmstadt, Germany
² Institut für Theoretische Physik, Universität Giessen, 35392, Giessen, Germany
³ GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstr. 1, 64291, Darmstadt, Germany
⁴ Institute for Nuclear Theory, University of Washington, Seattle, WA, 98195, USA

christian.fischer@physik.tu-darmstadt.de

Received: 27 October 2010
Published online: 18 November 2010

Abstract

We report on an analysis of the quark spectral representation at finite temperatures based on the quark propagator determined from its Dyson–Schwinger equation in Landau gauge. In Euclidean space we achieve nice agreement with recent results from quenched lattice QCD. We find different analytical properties of the quark propagator below and above the deconfinement transition. Using a variety of ansätze for the spectral function we then analyze the possible quasiparticle spectrum, in particular its quark mass and momentum dependence in the high temperature phase. This analysis is completed by an application of the Maximum Entropy Method, in principle allowing for any positive semi-definite spectral function. Our results motivate a more direct determination of the spectral function in the framework of Dyson–Schwinger equations.