  Perturbation theory for lattice fermions with domain wall mass terms is
developed and is applied to investigate the chiral Schwinger model formulated
on the lattice by Kaplan's method. We calculate the effective action for gauge
fields to one loop, and find that it contains a longitudinal component even for
anomaly-free cases. From the effective action we obtain gauge anomalies and
Chern-Simons current without ambiguity. We also show that the current
corresponding to the fermion number has a non-zero divergence and it flows off
the wall into the extra dimension. Similar results are obtained for a proposal
by Shamir, who used a constant mass term with free boundaries instead of domain
walls.
