The general one-loop structure for the LFV Higgs decays Hr→lalb in multi-Higgs models with neutrino masses

Abstract

In this paper, we present general formulae for the calculation of LFV Higgs decays [Formula: see text] at one-loop, with [Formula: see text] being part of the Higgs spectrum of a generic multi-scalar extension of the Standard Model (SM) with neutrino masses. We develop a method based on a classification of the particles appearing in the loop diagrams (scalars, fermions and vectors), and by identifying the corresponding couplings, we are able to present compact expressions for the form factors involved in the amplitudes. Our results are applicable to models where Flavor Changing Neutral Currents (FCNC) are forbidden at the tree level, but change of flavor is induced by charged currents. Then, as applications of our formalism, we evaluate the branching ratio for the mode [Formula: see text], for two specific models: the See-Saw Type I-[Formula: see text]SM and the Scotogenic model (here [Formula: see text] corresponds to the SM-like Higgs boson); we find that the largest branching ratio for SM-like Higgs [Formula: see text] boson within the [Formula: see text]SM is of the order [Formula: see text], while for the Scotogenic model we find [Formula: see text], which satisfy the latest experimental LHC results.