HEP Seminar - Axions in quantum field theory and quantum gravity
Matt Reece, Harvard
Abstract: Axions are of great interest as a potential solution to the Strong CP problem and a potential dark matter candidate. They are known to be common in string theory constructions. It can be useful to think of axions as gauge fields for a (-1)-form generalized global symmetry, namely, instanton number. I will use this viewpoint to discuss how axions interact with magnetic monopoles in QFT (and relatedly, why the axion coupling to photons is quantized), and to propose an explanation of the ubiquity of axions in quantum gravity.
