SELF-DUALITY IN MAXWELL-CHERN-SIMONS THEORIES WITH NON MINIMAL COUPLING WITH MATTER FIELD

We consider a general class of non-local MCS models whose usual minimal coupling to a conserved current is supplemented with a (non-minimal) magnetic Pauli-type coupling. We find that the considered models exhibit a self-duality whenever the magnetic coupling constant reaches a special value: the partition function is invariant under a set of transformations among the parameter space (the duality transformations) while the original action and its dual counterpart have the same form. The duality transformations have a structure similar to the one underlying self-duality of the (2+1)-dimensional Z_n-abelian Higgs model with Chern-Simons and bare mass term. The occurrence of a duality symmetry within a model may have interesting consequences, since it can be used to derive exact non-perturbative results and/or to obtain information on the corresponding phase diagram.