Naturalness-motivated composite Higgs model for generating the top Yukawa coupling

TL;DR

This paper proposes a composite Higgs model where the top Yukawa coupling arises from four-fermion operators, featuring new light gauge bosons and addressing naturalness without light top partners.

Contribution

It introduces a scalar-less dynamical composite Higgs model with a novel mechanism for the top Yukawa coupling via four-fermion operators and predicts new sub-TeV gauge bosons.

Findings

Presence of light gauge bosons $E_$ and $Z'_E$ at sub-TeV scale.

Model achieves naturalness with a low cutoff scale for top quark loops.

Rich phenomenology in top physics due to new gauge bosons.

Abstract

The large top Yukawa coupling results in the top quark contributing significantly to the quantum correction of the Higgs mass term. Traditionally, this effect is canceled by the presence of top partners in symmetry-based models. However, the absence of light top partners poses a challenge to the Naturalness of these models. In this paper, we study a model based on composite Higgs with the top Yukawa coupling originating from dimension-six four-fermion operators. The low cutoff scale of the top quark loop required by the Naturalness principle can be realized with a light gauge boson $E_\mu$ which connects the hyperfermions and top quarks. A scalar-less dynamical model with weakly coupled extended $SU(4)_{EC}$ gauge group is presented. The model features an $E_\mu$ boson and a $Z'_E$ boson both at the sub-TeV scale, which lead to a rich phenomenology, especially in the top physics.