Invertible and non-invertible generalized symmetry anomalies for pedestrians: a view from the torus

Abstract:

I will explain how quantizing a four-dimensional gauge theory on a spatial torus with twisted boundary conditions provides a simple and useful view of anomalies involving center symmetry and (invertible or non-invertible) chiral symmetries. I will show that these anomalies imply exact degeneracies in the torus Hilbert space. These degeneracies hold at any size torus and thus have implications for the infinite volume phase structure.