Theta Defects

Abstract

I will describe construction of theta defects, which are topological defects in possibly non-topological systems. Such defects arise as a consequence of a discrete gauging or condensation of a global symmetry S, and are in one-to-one correspondence with lower-dimensional topological systems protected by the symmetry S. Theta defects are universal in the sense that they exist in any system that can be obtained by gauging/condensing symmetry S of some other system. We will see that theta defects form fusion higher-categories, with prominent examples being higher-representations of groups and higher-groups. In a following talk, Apoorv Tiwari would describe a non-universal generalization known as twisted theta defects. Based on ArXiv: 2204.06564, 2208.05973, 2212.06159 and 2212.06842.