Regular effective action of gauge field theory and quantum gravity

We present a perturbative formalism for the effective quantum action of a general Fermi-Bose field theory. We propose a unitary alternative to the conventional virtual ghost prescription for handling the functional integral of gauge fields, based on the functional space metric that is determined by the Dirac brackets of the canonical theory. A gauge-invariant Gaussian cutoff is introduced by extending the functional space metric into a regular counterpart. The regular one-loop contributions of a scalar field to the photon and the graviton self-energies are computed. The otherwise logarithmically divergent contributions are found, in our scheme, to be independent of cutoff.