Motivated by recent advances in the generalization of global symmetries in quantum field theory, we introduce a class of selection rules originating from non-invertible fusion algebras rather than conventional group laws, which we refer to as non-invertible selection rules (NISRs). We discuss some applications in simple particle physics models, demonstrating that NISRs are far from exotic and can potentially have broad applications in addressing open questions beyond the Standard Model. We further illustrate their implications in perturbation theory through the spurion analysis and connect to aspects of effective theories and 't Hooft naturalness. This talk is based on 2503.19964, 2508.14970, 2510.18972.

Biography

Ling-Xiao Xu (徐凌霄) is currently a postdoc working at the Abdus Salam International Centre for Theoretical Physics (ICTP) in Trieste, Italy. Before that, he was a postdoc at the University of Padova and INFN Padova section, following a Ph.D. degree from Peking University in 2021. His research focuses on particle physics beyond the Standard Model, and more recently, implications of (generalized) symmetries and anomalies in quantum field theory.