The General One-loop Structure for the LFV Higgs Decays $H_r \to l_a l_b$ in multi-Higgs Models with Neutrino Masses

Abstract

In this paper we present the general formulae for the calculation of the one-loop LFV Higgs decays H r → l a l b , with H r being part of the Higgs spectrum of a generic multi-scalar extension of the Standard Model (SM). 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 amplitudes applicable to models where Flavor Changing Neutral Currents (FCNC) are forbidden at tree-level. Then, as applications of our formalism, we evaluate the branching ratio for the mode h → l a l b with (h = H 1 being the SM-like Higgs boson), for two specific models: the See-Saw Type I-νSM and the Scotogenic model. We find that the largest branching ratio for SM Higgs h boson within the νSM is of the order BR(h → µτ ) 10 −10 , while for the Scotogenic model we find BR(h → eτ ) 10 −8 , which satisfy the latest experimental LHC results.

Lepton flavor violating Z and Higgs decays in the scotogenic model

“…The method of computing the branching ratios for these decays and numerical study done on them in Ref. [54] are found to be different from what we have done in this work. After comparing Br(H → α β ) versus Br( α → β γ ) in Ref.…”

“…Note added: While this manuscript was under preparation, Ref. [54] had appeared where LFV decays of Higgs boson were studied in the scotogenic model. The method of computing the branching ratios for these decays and numerical study done on them in Ref.…”

“…After comparing Br(H → α β ) versus Br( α → β γ ) in Ref. [54], it is shown that the allowed values for Br( α → β γ ) are suppressed to around 10 −34 . Moreover, the branching ratio for H → μτ is also shown to be suppressed to around 10 −37 .…”

Lepton flavor violating $Z$ and Higgs decays in the scotogenic model

“…The method of computing branching ratios for these decays and numerical study on them in Ref. [29] are found to be different from what we have presented here.…”

“…The Note added: While this manuscript was under preparation, Ref. [29] had appeared where LFV decays of Higgs boson were studied in the scotogenic model. The method of computing branching ratios for these decays and numerical study on them in Ref.…”