Light-cone expansion for a product of two gauge-invariant currents in QCD

A light-cone expansion for a product of two gauge-invariant currents is obtained in quantum chromodynamics. The coefficient functions in the expansion are derived from the Green functions. This has resulted in the establishment of gauge invariance and in the possibility of estimating the coefficient functions in any order of the perturbation theory. A new way of presenting the most singular part of the expansion in gauge-invariant form has been invented.