Topological effects, dipole moments, and the dual current in 2+1 dimensions - art. no. 022102

We study the Aharonov-Casher effect and its electromagnetic-dual effect, in troduced by He, McKellar, and Wilkens, in 2 + 1 dimensions. In this restric ted space these effects are the result of the interaction of the electromag netic field tensor with the dual of a current. Transferring the dual operat ion from the current to the field tensor shows that this interaction may be reinterpreted as due to the interaction of an effective vector potential a nd a current. and the topological effects follow immediately. The restricti on to 2 + 1 dimensions, with this interpretation, provides a unified way of treating these topological effects for an arbitrary spin, and a general pr oof for this case is provided. Perhaps more interestingly the treatment sho ws that a spin-0 particle can show these effects, although it has no magnet ic or electric dipole moment in the usual sense.