Asymptotic solution of Schwinger -- Dyson equation for the gluon propagator in the infrared region

The equation for the gluon propagator in the approach of Baker-Ball-Zachariasen is considered. The possibility of non-integer power infrared behaviour is studied, $D(q) \sim (q^2)^{-c}$, $q^2 \rightarrow 0$. It is shown that the characteristic equation for the exponent has no solutions at $-1\leq c\leq 3$. The approximations made to obtain the closed integral equation are analysed and the conclusion on the infrared behaviour of the gluon propagator $D(q) \sim 1/(q^2)^2$, $q^2 \rightarrow 0$ is made when the transverse part of the triple gluon vertex is taken into account.