Radiatively-induced LFV Higgs Decays from Massive ISS Neutrinos

TL;DR

This paper investigates the potential for large lepton flavor violating Higgs decays within the inverse seesaw model, performing detailed one-loop calculations and analyzing parameter space constraints to identify observable decay rates at the LHC.

Contribution

It provides the first comprehensive one-loop analysis of LFV Higgs decays in the inverse seesaw model considering three pairs of massive neutrinos and detailed compatibility with experimental data.

Findings

LFV Higgs decay rates can reach up to 10^{-5}

Predicted rates are close to future LHC sensitivities

Constraints from neutrino data and LFV radiative decays are satisfied

Abstract

In the inverse seesaw model (ISS), the smallness of the neutrino masses is related to the smallness of a lepton number violating mass term whilst the seesaw scale is naturally close to the TeV scale, which allows for large effects in lepton flavor and universality violating observables. With the ongoing and planned measurements of the Higgs boson properties at the LHC, we found timely to investigate the possibility of having large lepton flavor violating Higgs decay (LFVHD) rates within the context of the ISS, considering the most generic case where three additional pairs of massive right-handed singlet neutrinos are added to the Standard Model particle content. We present a full one-loop computation of the LFVHD rates and analyze in full detail the predictions as functions of the various relevant ISS parameters, which are required to be compatible with the present neutrino data and the present experimental bounds for the three LFV radiative decays, and also consistent with other constraints, like perturbativity of the neutrino Yukawa couplings. At the end, we conclude on the maximum allowed LFVHD rates within the ISS, which may reach maximal values of order $10^{-5}$ for the $H \to e \bar \tau$ and $H \to \mu \bar \tau$ channels, close to the expected future LHC sensitivities.