Double logarithmic asymptotic behavior of vertex functions in quantum chromodynamics. II. Eighth order of perturbation theory

The method of calculating the double logarithmical asymptotics of vertex functions suggested by the authors in $[1,\,2]$, is applied to the problem of calculating the singlet formfactor of a quark in the 8th order of the perturbation theory. It is shown that this formfactor is exponentiated within the 8th order.