Light composite Higgs boson from the normalized Bethe-Salpeter equation

TL;DR

This paper investigates the mass of composite Higgs bosons in walking technicolor theories using the normalized Bethe-Salpeter equation, revealing that normalization effects significantly influence the predicted scalar masses.

Contribution

It introduces the importance of the BSE normalization condition in calculating scalar masses in walking technicolor models, extending previous methods.

Findings

Composite Higgs masses can be near experimental exclusion limits.

Normalization effects alter scalar mass predictions in walking theories.

Models with fundamental technifermions may be experimentally constrained.

Abstract

Scalar composite boson masses have been computed in QCD and Technicolor theories with the help of the homogeneous Bethe-Salpeter equation (BSE), resulting in a scalar mass that is twice the dynamically generated fermion or technifermion mass ($m_{dyn}$). We show that in the case of walking (or quasi-conformal) technicolor theories, where the $m_{dyn}$ behavior with the momenta may be quite different from the one predicted by the standard operator product expansion, this result is incomplete and we must consider the effect of the normalization condition of the BSE to determine the scalar masses. We compute the composite Higgs boson mass for several groups with technifermions in the fundamental and higher dimensional representations and comment about the experimental constraints on these theories, which indicate that models based on walking theories with fermions in the fundamental representation may, within the limitations of our approach, have masses quite near the actual direct exclusion limit.