Constraining on dynamical electroweak symmetry breaking via R_b

TL;DR

This paper develops a framework to evaluate constraints from Z boson decay into bottom quarks on technicolor models with strong gauge interactions, focusing on the roles of vector and axial vector mesons.

Contribution

It introduces a general method to analyze flavor constraints in technicolor theories, incorporating vector and axial vector meson effects for the first time.

Findings

Constraints significantly limit technicolor model parameters.

Vector and axial vector mesons impact Z→bb decay rates.

Framework aids in assessing viability of dynamical electroweak symmetry breaking.

Abstract

New strong gauge interactions remain a viable source for the electroweak symmetry breaking. However, addressing the generation of fermion masses remains a challenge. A basic observable which provides stringent constraints on the flavor extensions of Technicolor-type models is the decay rate of the Z boson into a bbbar-pair. In this paper we provide a general framework to evaluate the resulting constraints on the technicolor theory level taking into account the contributions from the vector and axial vector mesons and discuss the consequences for phenomenology.