  Gribov's scenario of supercritical charges in QCD is investigated. We perform
a numerical study of the corresponding equation for the Green function of light
quarks. This is done in an approximation which neglects all pion contributions.
Different types of solutions in the Euclidean region are discussed and the mass
function of the quark is calculated. The solutions of the equation are shown to
have a qualitatively different behaviour if the strong coupling constant
alpha_s exceeds a critical value alpha_c = 0.43 in the infrared region. Chiral
symmetry breaking is found to occur at supercritical coupling. The analytic
structure of the solutions is investigated. Earlier results obtained by Gribov
are confirmed and extended.
