Dynamical chiral-symmetry breaking at T = 0 and T ≠ 0 in the Schwinger-Dyson equation with lattice QCD data
Faculty of Science, Tokyo Institute of Technology, Ohkayama 2-12-1, Meguro, 152-8551, Tokyo, Japan
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Accepted: 21 September 2004
Published online: 3 December 2004
Dynamical chiral-symmetry breaking (DCSB) in QCD is investigated in the Schwinger-Dyson (SD) formalism based on lattice QCD data. From the quenched lattice data for the quark propagator in the Landau gauge, we extract the SD integral kernel function, the product of the quark-gluon vertex and the polarization factor in the gluon propagator, in an Ansatz-independent manner. We find that the SD kernel function exhibits the characteristic behavior of nonperturbative physics, such as infrared vanishing and strong enhancement at the intermediate-energy region around p ∼ 0.6GeV. The infrared and intermediate energy region (0.4GeV < p < 1.5GeV) is found to be most relevant for DCSB from analysis on the relation between the SD kernel and the quark mass function. We apply the lattice-QCD-based SD equation to thermal QCD, and calculate the quark mass function at the finite temperature. Spontaneously broken chiral symmetry is found to be restored at high temperature above 110 MeV.
PACS: 12.38.Aw General properties of QCD (dynamics, confinement, etc.) – / 12.38.Lg Other nonperturbative calculations – / 12.38.Mh Quark-gluon plasma – / 12.38.-t Quantum chromodynamics –
© Società Italiana di Fisica and Springer-Verlag, 2005