Generating functionals for Green's functions in gauge field theories

Structure of generating functionals of one-particle irreducible Green's functions in gauge field theories is investigated. Axial as well as covariant gauge conditions are considered. In both cases general structure of the functionals is obtained and functional expansion over nonlocal operators is given. In the case of covariant gauge the arising of gauge-dependent operators follows in a natural way from the structure of the corresponding functional.