Zero modes in non local domain walls
  We generalize the Callan-Harvey mechanism to the case of actions with a non local mass term for the fermions. Using a 2+1-dimensional model as a concrete example, we show that both the existence and properties of localized zero modes can also be consistently studied when the mass is non local. We derive some general properties from a study of the resulting integral equations, and consider their realization in a concrete example. 
C. D. Fosco, G. Torroba