Model-independent constraints on exotic particle masses from lepton decays and the role of interference

Abstract

Together with every Beyond the Standard Model ultraviolete complete, renormalizable model, several exotic particles are usually hypothesized. CP -even neutral and doubly-charged scalars are common, well-known examples which can contribute to the seven 3-body Charged Lepton Flavor Violating decays. The experimental bounds on each Branching Ratio within this set of processes provide a good test for new physics that can induce powerful constraints on relevant parameter spaces. This is specially true for a third species of particle which, unlike the previous two, is a rare feature of renormalizable models: a doubly charged vector bilepton. We show how these purely leptonic bounds can indeed induce relevant exclusion regions for the corresponding particles masses, stronger than what have been considered in the literature, and examine how interference effects can influence these regions in a non-trivial way.

Neutrino physics and non-standard interactions

“…All these processes discussed above have contributions from neutral and charged scalars that in general are not negligible [57].…”