Coupling a Cosmic String to Topological Quantum Field Theory

Watch a 29-minute physics lecture from Harvard CMSA's Workshop on Phase Transitions and Topological Defects in the Early Universe where Sungwoo Hong from the University of Chicago explores the coupling of cosmic strings to topological field theory (TQFT). Delve into how recent developments in understanding generalized symmetry and higher-form symmetry have revolutionized our comprehension of Quantum Field Theory (QFT), particularly its IR phases. Learn about various methods of coupling axion-Maxwell theory to TQFT, challenging conventional wisdom by demonstrating how topological modifications can directly impact local physics with observable consequences. Examine how dimensional reduction allows TQFT coupling in 4D to significantly affect 2D string world-sheet QFT, and discover how gauging discrete subgroups of 0-form shift symmetry can alter cosmic string spectra. The lecture concludes with discussions on generalized symmetries and associated higher-groups within these theoretical frameworks.