Lepton flavor violation in the Simplest Little Higgs model

TL;DR

This paper investigates lepton flavor violation in the Simplest Little Higgs model, calculating key processes and comparing results with other models, highlighting the need for flavor alignment or high energy scales.

Contribution

It provides the first detailed analysis of lepton flavor violation in the SLH model, including Feynman rules and leading contributions to rare processes.

Findings

Results are comparable to the Littlest Higgs with T parity model.

Flavor violation effects require Yukawa coupling alignment or a scale around 10 TeV.

Lepton flavor violation arises at the one-loop level in the SLH model.

Abstract

The flavor sector of Little Higgs models based on product groups, notably the Littlest Higgs with T parity (LHT), has been extensively studied and some amount of fine tuning was found to be required to meet the experimental constraints. However, no such attention has been paid to other classes of models. Here we analyze the phenomenology of flavor mixing in the lepton sector of a simple group model, the Simplest Little Higgs (SLH). We obtain the Feynman rules of the SLH in the 't Hooft-Feynman gauge up to the necessary order and calculate the leading contributions to the rare processes mu -> e gamma, mu -> eee and mu-e conversion in nuclei. We find results comparable to those of the LHT model, because in both cases they arise at the one-loop level. These require the flavor alignment of the Yukawa couplings of light and heavy leptons at the per cent level or an effective scale of around 10 TeV.