Hidden fine tuning in the quark sector of little higgs models

TL;DR

This paper examines the fine-tuning issues in little Higgs models, revealing that gauge interactions break the collective symmetry essential for protecting the Higgs mass, thus challenging the naturalness of these models.

Contribution

It demonstrates that the collective symmetry in little Higgs models is inherently broken by gauge interactions, requiring fine-tuning for the top quark mass generation.

Findings

Fine-tuning is necessary in the littlest Higgs model due to symmetry breaking.

Gauge interactions break the collective symmetry protecting the Higgs.

The problem is generic across similar models.

Abstract

In little higgs models a collective symmetry prevents the higgs from acquiring a quadratically divergent mass at one loop. By considering first the littlest higgs model we show that this requires a fine tuning: the couplings in the model introduced to give the top quark a mass do not naturally respect the collective symmetry. We show the problem is generic: it arises from the fact that the would be collective symmetry of any one top quark mass term is broken by gauge interactions.