Models and phenomenology of flavourful axions
By Fredrik Björkeroth (INFN - Laboratori Nazionali di Frascati)
Tuesday 11 Dec
I discuss two examples of how a Peccei-Quinn (PQ) symmetry, the current favourite candidate for solving the strong CP problem, arises from flavour symmetries that shape the Standard Model Yukawa operators. In one, the PQ symmetry results accidentally from a non-Abelian discrete family symmetry, within a Pati-Salam model which also unifies quarks and leptons. In the other, the PQ symmetry is identified as a horizontal U(1) symmetry acting on the quarks, enforcing a maximal reduction in the number of free Yukawa parameters. In both cases, the fermions have generation-dependent PQ charges, leading to flavour-violating couplings with the axion, which may be detected in heavy meson and lepton decays, along with traditional axion searches.