One-loop flavor change in Little Higgs models

TL;DR

This paper examines how Little Higgs models, designed to address fine-tuning in the Higgs sector, face significant constraints from experimental limits on lepton flavor-changing processes at the one-loop level.

Contribution

It provides a detailed analysis showing that Little Higgs models are incompatible with experimental lepton flavor mixing constraints under naturalness assumptions.

Findings

Little Higgs models are constrained by lepton flavor mixing limits.

One-loop predictions for flavor-changing processes challenge model viability.

Two different Little Higgs models are analyzed in detail.

Abstract

The Little Higgs (LH) idea attempts to cure the little amount of fine-tuning necessary to bridge the gap between the Higgs mass (electroweak scale) and the new physics scale suggested by electroweak precision tests (~10 TeV). However, we show that LH models do not survive the confrontation with experimental limits on lepton flavor mixing, assuming the same naturalness arguments that motivate their introduction. Two different LH models are analyzed and several aspects of their one-loop predictions for lepton flavor-changing processes are discussed.