Infrared behaviour of gluon and ghost propagators in QCD in the Landau gauge

Abstract

Non-perturbative formalism of the generalized effective action is used for deriving the Schwinger-Dyson equations. In order to clear the domain of integration in the functional integral from gauge copies a restriction to the Gribov horizon due to Zwanziger is implemented. In this approach an asymptotic behaviour of gluon propagator and propagator of the Faddeev-Popov ghosts at small momenta is studied. Such a behaviour is obtained as a result of solving coupled Schwinger-Dyson equations in zeroth and first-order approximation. The qualitative agreement of these results with the ones obtained before is demonstrated and quantitative difference in some coeffcients is found.