Probing lepton flavour violation with Higgs boson decays H-> li+lj

TL;DR

This paper investigates lepton flavour violating Higgs decays in various models, finding potential branching ratios up to 0.1 for certain channels, which could be detectable in future experiments.

Contribution

It provides a comprehensive analysis of LFV Higgs decays across multiple models, including effective operators and specific extensions like the two-Higgs doublet model.

Findings

H->tau mu and H->tau e can have branching ratios around 0.1.

Current bounds strongly constrain e-mu LFV decays, with B.R. around 10^-9.

LFV Higgs decays are significantly suppressed in the Standard Model with neutrino masses.

Abstract

We evaluate the lepton flavour violating (LFV) decays of HIggs bosons H->li+lj in several extensions of the SM, including both the effective lagrangian approach and several specific models. For the effective lagrangian case, we focus on dimension-six operators that induce LFV vertices for the Higgs and or Z bosons. For those operators whose coefficients can not be constrained by present data, LFV Higgs decays can have a B.R. of order 0.1-0.01. Those cases when current bounds apply, induce strong bounds for e-mu transitions, and the b.r. for H->e mu is of order 10^-9; however H->tau mu, tau e, can have B.R. of order 0.1. In the case of the two-higgs doublet model III, we obtain a similar B.R. for H-> tau mu, tau e, whereas in the SM with massive neutrinos and the minimal SUSY-SM the corresponding B.R. are very suppressed.