$H\to \ell\ell'$ in the Simplest Little Higgs Model

TL;DR

The paper analyzes lepton flavor violating Higgs decays in the Simplest Little Higgs Model, finding that observing such decays at the LHC would challenge the model's validity due to its suppressed predictions.

Contribution

It provides the first detailed prediction of $H o au ext{ } ext{or} ext{ } ext{ell'}$ decays within the Simplest Little Higgs Model and assesses their experimental detectability.

Findings

Predicted $H o au ext{ } ext{or} ext{ } ext{ell'}$ decay rates are very suppressed.

Observation of these decays at the LHC would disfavor the model.

The model's predictions are consistent with suppressed lepton flavor violating tau decays.

Abstract

Little Higgs Models are promising constructs to solve the hierarchy problem affecting the Higgs boson mass for generic new physics. However, their preservation of lepton universality forbids them to account for the $H\to\tau\mu$ CMS hint and at the same time respect (as they do) the severe limits on $H\to\mu e$ inherited from the non-observation of $\mu\to e\gamma$. We compute the predictions of the Simplest Little Higgs Model for the $H\to \ell\ell'$ decays and conclude that the measurement of any of these decays at LHC (even with a much smaller rate than currently hinted) would, under reasonable assumptions, disfavor this model. This result is consistent with our earlier observation of very suppressed lepton flavor violating semileptonic tau decays within this model.