Conformal little Higgs models

TL;DR

This paper proposes a unified conformal framework that naturally completes little Higgs models at high energies, addressing the hierarchy problem, flavor puzzles, and ensuring UV fixed points without fine-tuning.

Contribution

It introduces a conformal symmetry-based UV completion for little Higgs models, automatically ensuring UV fixed points and addressing flavor puzzles.

Findings

Framework naturally addresses the electroweak hierarchy problem.

Ensures the presence of UV fixed points without fine-tuning.

Allows UV completion of all known little Higgs models via conformal dynamics.

Abstract

Little Higgs models address the hierarchy problem by identifying the SM Higgs doublet as pseudo-Nambu--Goldstone bosons (pNGB) arising from global symmetries with collective breakings. These models are designed to address the little hierarchy problem up to a scale of $\Lambda\!\sim\! {\cal O}(10)$ TeV. Consequently, these models necessitate an ultraviolet (UV) completion above this scale. On the other hand, conformal extensions of the Standard Model are intriguing because scales emerge as a consequence of dimensional transmutation. In this study, we present a unified framework in which the electroweak hierarchy problem is tackled through a conformal symmetry collectively broken around the TeV scale, offering an appealing UV completion for little Higgs models. Notably, this framework automatically ensures the presence of the required UV fixed points, eliminating the need for careful adjustments to the particle content of the theory. Moreover, this framework naturally addresses the flavor puzzles associated with composite or little Higgs models. Furthermore, we suggest that in this framework all known little Higgs models can be UV-completed through conformal dynamics above the scale $\Lambda$ up to arbitrary high scales.