Shu-Heng Shao, Institute for Advanced Study


Past Event

Shu-Heng Shao, Institute for Advanced Study

September 10, 2018
2:10 PM - 3:10 PM
Pupin Hall Theory Center, 8th Floor

The Power of Non-Symmetry

Global symmetries in two dimensions are implemented by topological defect lines (TDLs). For continuous global symmetries, the TDLs are nothing but the Noether charges. However there can be TDLs that are not associated to any global symmetry, and can be thought of as a generalized notion of symmetry. We study the crossing relations of TDLs, discuss their relation to the 't Hooft anomaly, and use them to constrain renormalization group flows to either conformal critical points or topological quantum field theories (TQFTs). We show that if certain non-symmetry TDLs are preserved along a RG flow, then the vacuum cannot be a non-degenerate gapped state.