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

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 $E_{\mu }$ that connects the hyperfermions and top quarks. A scalarless dynamical model with weakly coupled extended $SU(4{)}_{EC}$ gauge group is presented. The model features an $E_{\mu }$ boson and a $Z_E^{\prime }$ boson both at the sub-TeV scale, which lead to a rich phenomenology, especially in the top quark physics.