Symmetry Lost and Found
APA
Shao, S. (2023). Symmetry Lost and Found. Perimeter Institute. https://pirsa.org/23030078
MLA
Shao, Shu-Heng. Symmetry Lost and Found. Perimeter Institute, Mar. 28, 2023, https://pirsa.org/23030078
BibTex
@misc{ pirsa_PIRSA:23030078, doi = {10.48660/23030078}, url = {https://pirsa.org/23030078}, author = {Shao, Shu-Heng}, keywords = {Quantum Fields and Strings}, language = {en}, title = {Symmetry Lost and Found}, publisher = {Perimeter Institute}, year = {2023}, month = {mar}, note = {PIRSA:23030078 see, \url{https://pirsa.org}} }
In massless QED, we find that the classical U(1) axial symmetry is not completely broken by the Adler-Bell-Jackiw anomaly. Rather, it is resurrected as a generalized global symmetry labeled by the rational numbers. Intuitively, this new global symmetry in QED is a composition of the naive axial rotation and a fractional quantum Hall state. The conserved symmetry operators do not obey a group multiplication law, but a non-invertible fusion algebra. We further generalize our construction to QCD, and show that the neutral pion decay can be derived from a matching condition of the non-invertible global symmetry. Finally, we find a non-invertible Gauss law in axion-Maxwell theory.
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