Flavour Violating Higgs Decays
Dr. Joachim Kopp (MPI Heidelberg)

Flavour violating couplings of the Higgs boson to quarks or leptons are generically expected in many extensions of the Standard Model, for instance in multi-Higgs doublet models, extra-dimensional scenarios, and models of compositeness. In this talk, we derive a comprehensive set of constraints on flavour violating Higgs couplings using data on meson oscillations, rare decays, dipole moments and other precision observables. While these low-energy constraints are very strong for processes involving only electrons, muons or light quarks, Higgs couplings to top quarks and tau leptons can still be very large. In fact, the strongest limits on processes like t -> h q, h -> tau mu and h -> tau e are already coming from the LHC. We derive concrete bounds on h -> tau mu and h -> tau e by recasting the ATLAS search for h -> tau tau, and we demonstrate how a dedicated search for lepton flavour violating Higgs decays can achieve a substantially improved sensitivity even with existing data alone.