ON THE OVERLAP PRESCRIPTION FOR LATTICE REGULARIZATION OF CHIRAL FERMIONS

Feynman rules for the vacuum amplitude of fermions coupled to external gauge and Higgs fields in a domain wall lattice model are derived usi ng time-dependent perturbation theory. They have a clear and simple st ructure corresponding to 1-loop vacuum graphs. Their continuum approxi mations are extracted by isolating the infrared singularities and it i s shown that, in each order, they reduce to vacuum contributions for c hiral fermions. In this sense the lattice model is seen to constitute a valid regularization of the continuum theory of chiral fermions coup led to weak and slowly varying gauge and Higgs fields. The overlap amp litude, while not gauge invariant, exhibits a well defined (module pha se conventions) response to gauge transformations of the background fi elds. This response reduces in the continuum limit to the expected chi ral anomaly, independently of the phase conventions.