Scalar Decay Constant and Yukawa Coupling in Walking Gauge Theories

TL;DR

This paper calculates the yukawa coupling in walking gauge theories using nonperturbative methods, revealing its potential enhancement over the Standard Model and implications for scalar production at the LHC.

Contribution

It introduces a nonperturbative approach to compute the yukawa coupling in walking technicolor models, linking scalar decay constants and chiral condensates.

Findings

Yukawa coupling can be larger or smaller than SM value depending on model parameters.

In one-family technicolor models near conformality, the yukawa coupling is slightly larger than SM.

Scalar production via gluon fusion can be significantly enhanced, aiding discovery at the LHC.

Abstract

We propose an approach for the calculation of the yukawa coupling through the scalar decay constant and the chiral condensate in the context of the extended technicolor (ETC). We perform the nonperturbative computation of the yukawa coupling based on the improved ladder Schwinger-Dyson equation. It turns out that the yukawa coupling can be larger or smaller than the standard model (SM) value, depending on the number $N_D$ of the weak doublets for each technicolor (TC) index. It is thus nontrivial whether or not the huge enhancement of the production of the scalar via the gluon fusion takes place even for a walking TC model with a colored techni-fermion. For the typical one-family TC model near conformality, it is found that the yukawa coupling is slightly larger than the SM one, where the expected mass of the scalar bound state is around 500 GeV. In this case, the production cross section via the gluon fusion is considerably enhanced, as naively expected, and hence such a scalar can be discovered/excluded at the early stage of the LHC.