Top quark induced vacuum misalignment in little higgs models

TL;DR

This paper investigates how the top quark influences vacuum alignment in little Higgs models, showing it can dominate over gauge effects and affect model parameters and hierarchy.

Contribution

It demonstrates the top quark's dominant role in vacuum alignment in specific little Higgs models and derives bounds on gauge couplings to ensure correct vacuum selection.

Findings

Top quark effects can override gauge sector in vacuum alignment.

Bounds on gauge couplings are derived to maintain proper vacuum alignment.

In models with T parity, the top quark allows for smaller gauge couplings.

Abstract

We show that the effect of the top quark can dominate over the effect of the gauge sector in determining the vacuum alignment in little higgs (LH) models. We demonstrate that in the littlest LH model and the SU(2)xSU(2)xU(1) LH model, ensuring that the correct vacuum alignment is chosen requires that a subset of the gauge sector couplings be large to overcome the effect of the top quark. We quantify this effect by deriving bounds on the couplings in the gauge sector and demonstrate that these bounds provide a compelling theoretical reason for the gauge coupling constant hierarchy in the SU(2)xSU(2)xU(1) model that reduces the Goldstone decay constant scale to a TeV. We also argue that for a class of LH models with T parity the top quark drives the correct vacuum alignment and therefore all gauge couplings can be small.