Time: 14:00-15:30  (Beijing time), Monday, 2026/1/12 (Jan 12)
Location: N306, Teaching Building, UCAS Zhongguancun Campus

Speaker: Yu-An Chen, Peking University

Abstract: In quantum field theory, a global symmetry is said to possess a ’t Hooft anomaly if it cannot be consistently gauged. This obstruction can be resolved by coupling the theory to a symmetry-protected topological (SPT) phase in one higher dimension. The influential work of Else and Nayak (2014) introduced a method for extracting anomalies of 0-form symmetries on lattice systems. However, extending this approach to higher-form symmetries has remained an open problem. In this talk, we will present a recent construction from our work that addresses this challenge. Our framework generalizes the spirit of Else–Nayak to 1-form symmetries on the 2-dimensional spatial lattice, providing a way of extracting an anomaly index through dimensional reduction. We will also generalize the concept of onsiteness to higher-form symmetries, and clarify the onsiteability criterion for 1-form symmetries in (2+1)D. We demonstrate that there is an
equivalence between onsiteability and the possibility of higher gauging.

Link for Zoom meeting:

https://us06web.zoom.us/j/85715129440?pwd=QlJJRFBWWFRLMkxCVmcxZ1RKdlRxQT09

Meeting ID: 857 1512 9440
Passcode: 501105