Domain wall fermions in a waveguide: The phase diagram at large Yukawa coupling.

In this paper we return to a model with domain wall fermions in a waveguide. This model contains a Yukawa coupling y which is needed for gauge invariance. A previous paper left the analysis for large values of this coupling incomplete. We fill the gap by developing a systematic expansion suitable for large y, and using this, we gain an analytic understanding of the phase diagram and fermion spectrum. We find that in a sense all the species doublers come back for large y. The conclusion that no lattice chiral gauge theory can be obtained from this approach therefore remains valid.