VACUUM POLARIZATION AND CHIRAL LATTICE FERMIONS

The vacuum polarization due to chiral fermions on a 4-dimensional Eucl idean lattice is calculated according to the overlap prescription. The fermions are coupled to weak and slowly varying background gauge and Higgs fields, and the polarization tensor is given by second order per turbation theory. In this order the overlap constitutes a gauge-invari ant regularization of the fermion vacuum amplitude. Its low-energy-lon g-wavelength behaviour can be computed explicitly and we verify that i t coincides with the Feynman graph result obtainable, for example, by dimensional regularization of continuum gauge theory. In particular, t he Standard Model Callan-Symanzik RG functions are recovered. Moreover , there are no residual lattice artefacts such as a dependence on Wils on-type mass parameters.