Anomalies in Fermionic UV Completions of Little Higgs Models

TL;DR

This paper analyzes fermionic UV completions of little Higgs models, focusing on anomalies and T-parity violations, and explores strategies to achieve anomaly-free models or stable particles despite anomalies.

Contribution

It demonstrates the unlikelihood of QCD-like UV completions being anomaly-free and proposes alternative multi-link moose models with modified T-parity for stable particles.

Findings

QCD-like UV completions are unlikely to be anomaly-free due to vacuum alignment issues.

Certain multi-link moose models can have a modified T-parity that stabilizes particles.

A potential collider discriminant for anomalous decays is discussed.

Abstract

We consider fermionic UV completions of little Higgs models and their associated T-parity violating anomalous vertices. In particular, we investigate strategies to avoid such parity-violating anomalies. We show that it is unlikely a QCD-like UV completion could be used to implement a model with anomaly-free global symmetry groups. This is because the vacuum state is unlikely to achieve the necessary alignment. However, we will see that certain multi-link moose models, although anomalous, possess a modified form of T-parity that leads to a stable particle. Finally, we briefly discuss a discriminant for detecting anomalous decays at colliders.