Chiral symmetry breaking in Gribov's approach to QCD at low momentum

We consider Gribov's equation for inverse quark Green function with and without pion correction. With polar parametrization of inverse quark Green function, we relate the dynamical mass function without pion correction, $M_{0}(q^2)$ and with pion correction, $M(q^2)$ at low momentum. A graph is plotted for $M(q^2)$ and $M_{0}(q^2)$ with q for low momentum. It is found that at low momenta pion corrections are small.