On Composite fields approach to Gribov copies elimination in Yang-Mills theories

We suggest a method of introducing the Gribov--Zwanziger horizon functional, $H$, for Yang--Mills theories by using the composite fields technique: $\sigma (\phi )=H$. A different form of the same horizon functional in gauges $\chi $ and $\chi ^{\prime }$ is taken into account via (gauged) field-dependent BRST transformations connecting quantum Yang--Mills actions in these gauges. We introduce generating functionals of Green's functions with composite fields and derive the corresponding Ward identities. A study of gauge dependence shows that the effective action in Yang--Mills theories with the composite field $H$ does not depend on the gauge on the extremals determined by the Yang--Mills fields $\phi $ alone.