ABSTRACT
In this talk, I will introduce the notion of global aspects in the physics of particles and topological defects. A well-known example is the global structure ambiguity of the Standard Model (SM) gauge group. I will discuss the correlation between the quantization conditions of axion–gauge couplings and this global structure.
As another example, I will describe how various global structures play important roles in the domain wall problem of the DFSZ axion model. A precise identification of the axion string–domain wall network—and hence the true nature of the domain wall problem—becomes possible by recognizing an overlap between the PQ symmetry and the SM gauge group.
An elegant solution to the domain wall problem can also be realized by introducing a global structure shared between the color and family gauge groups, which gives rise to discrete non-invertible PQ symmetries. The latter can then be slightly broken through UV completion in the form of an SU(9) color–flavor unification.
If time permits, I will also discuss group-theoretic methods for analyzing topological sectors and global structures in Grand Unified Theories.
BIOGRAPHY
Sungwoo Hong is currently an assistant Professor at Korea Advanced Institute of Science and Technology. Before coming to KAIST, he earned his PhD from the University of Maryland, and held postdoctoral fellowships at the University of Chicago, Argonne National Laboratory and Cornell University. His research interests include new theories of dark Matter and their phenomenology, on-shell scattering amplitudes, and generalized global symmetries.
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