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FIZIKA B 13 (2004) 1, 65 - 74
 
THE KUGO-OJIMA CONFINEMENT CRITERION
AND THE INFRARED BEHAVIOUR OF LANDAU GAUGE QCD
REINHARD ALKOFERa and CHRISTIAN S. FISCHERa,b
aUniversität Tübingen, Institut für Theoretische Physik,
Auf der Morgenstelle 14, D-72076 Tübingen, Germany
E-mail address: Reinhard.Alkofer@uni-tuebingen.de
bUniversität Heidelberg, Institut für Theoretische Physik,
Philosophenweg 16, D-69120 Heidelberg, Germany
E-mail address: chfi@tphys.physik.uni-tuebingen.de
Received 27 August 2003; Accepted
26 April 2004
Online 16 July 2004
Recent investigations of the Dyson-Schwinger equations and Monte-Carlo lattice
calculations resulted in a coherent description of the fully dressed gluon, ghost and
quark propagators in Landau gauge QCD. In the Dyson-Schwinger approach, the infrared
behaviour of these propagators is determined analytically. For finite spacelike momenta
the gluon, ghost and quark propagators are compared to available corresponding results of
lattice Monte-Carlo calculations. For all three propagators, an almost quantitative
agreement is found. These results for the non-perturbative propagators allow an analytical
verification of the Kugo-Ojima confinement criterion. Our numerical analysis clearly
reveals positivity violation for the gluon propagator generated by a cut in the complex
momentum plane. The non-perturbative strong running coupling resulting from these
propagators possesses an infrared fixed point. The quark propagator obtained from quenched
and unquenched calculations displays dynamical chiral symmetry breaking with quark masses
close to "phenomenological" and lattice values. We confirm that linear
extrapolations of the quark propagator for different bare masses to the chiral limit are
inaccurate.
PACS numbers: 02.30.Rz, 11.10.Gh, 12.38.Aw, 14.70.Dj
UDC 539.12.1
Keywords: confinement, Dyson-Schwinger equations, dynamical chiral symmetry breaking
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