Title: Global Structure of Symmetries in Particle Physics

Abstract: As particle physicists we usually think about small fluctuations of fields, but the phenomenology of our theories can depend crucially on the global structure of the field space. First I’ll discuss an ambiguity in the Standard Model gauge group, whose different versions make different model-independent predictions for the existence of fractionally charged particles. Such signatures at the LHC merit further attention from experimentalists and phenomenologists, as these particles can both reveal the structure of the SM, and falsify theories of unification. Then I’ll turn to axion theories and, as an example, the DFSZ model, where careful examination of global properties of the scalars and the gauge group can affect the structure of axion strings, and resolve the cosmological domain wall problem.

https://lbnl.zoom.us/j/94928022788?pwd=emVQWG1mTnhSbHVqekVuenk0VEVQZz09