Some examples in the realization of symmetry

Abstract

I briefly discuss three phenomena arising in recent work where the realization of symmetries in quantum mechanics is unusual. The first of these is, I believe, the very simplest realization of non-trivial confinement by a mechanism of charge-flux frustration. It arises in models having several coupled abelian Chern-Simons gauge symmetries, which closely resemble effective theories used for the quantum Hall effect. The second is symmetry obstruction by non-abelian flux, which has implications for 2+1 dimensional supergravity. Third is the possibility of new varieties of quantum statistics: non-abelian and projective.