Tadpole-Induced Electroweak Symmetry Breaking and pNGB Higgs Models

TL;DR

This paper explores a new mechanism for electroweak symmetry breaking in pNGB Higgs models, using a tadpole from an auxiliary sector to reduce fine-tuning and achieve more natural models with testable predictions at the LHC.

Contribution

It introduces a tadpole-induced EWSB mechanism that alleviates fine-tuning in pNGB Higgs models, with explicit examples in Twin and Composite Higgs frameworks.

Findings

Reduces fine-tuning in pNGB Higgs models

Predicts new Higgs and vector states at LHC13

Achieves natural hierarchy with $f_\Sigma \ll v_H \ll f_H$

Abstract

We investigate induced electroweak symmetry breaking (EWSB) in models in which the Higgs is a pseudo-Nambu-Goldstone boson (pNGB). In pNGB Higgs models, Higgs properties and precision electroweak measurements imply a hierarchy between the EWSB and global symmetry-breaking scales, $v_H \ll f_H$. When the pNGB potential is generated radiatively, this hierarchy requires fine-tuning to a degree of at least $\sim v_H^2/f_H^2$. We show that if Higgs EWSB is induced by a tadpole arising from an auxiliary sector at scale $f_\Sigma \ll v_H$, this tuning is significantly ameliorated or can even be removed. We present explicit examples both in Twin Higgs models and in Composite Higgs models based on $SO(5)/SO(4)$. For the Twin case, the result is a fully natural model with $f_H \sim 1$ TeV and the lightest colored top partners at 2 TeV. These models also have an appealing mechanism to generate the scales of the auxiliary sector and Higgs EWSB directly from the scale $f_H$, with a natural hierarchy $f_\Sigma \ll v_H \ll f_H \sim{\rm TeV}$. The framework predicts modified Higgs coupling as well as new Higgs and vector states at LHC13.