Gauge theories in the light-cone representation

We attempt in McCartor and Robertson's framework to formulate a perturbation theory of light-cone axial gauge QED in which zero-mode fields play roles as regulator fields yielding well-defined Mandelstam-Leibbrandt form of gauge field propagator. We find that zero-mode fields make up for degrees of freedom of A(+) and its canonical conjugate in the light-cone temporal gauge formulation and that they are retained in the interaction term j(+) A(+) through A(+), if and only if the integral integral(-infinity)(infinity)dx(-)j(-) does not vanish. It is pointed out that from the boundary surface contributions T++(x(-) = +/-infinity), which are added to obtain P+ identical to those in ordinary coordinates, an infinite number of noncovariant interaction terms might be obtained so as to cancel corresponding infinite number of noncovariant diagrams yielded by the contact term of the Fermion propagator.