Differential cross section for Aharonov--Bohm effect with non standard boundary conditions

A basic analysis is provided for the differential cross section characterizing Aharonov--Bohm effect with non standard (non regular) boundary conditions imposed on a wave function at the potential barrier. If compared with the standard case two new features can occur: a violation of rotational symmetry and a more significant backward scattering.Comment: to appear in Europhys. Let