$$Z \to b\bar b$$ probability and asymmetry in a model of dynamical electroweak symmetry breaking

Abstract

The deviations from the Standard Model in the probability of \(Z \to b\bar b\) decay and in the forward-backward asymmetry in the reaction \(e^ + e^ - \to b\bar b\) are studied in the framework of the model of dynamical electroweak symmetry breaking, the essential feature of which is the existence of a triple anomalous W-boson vertex in a region of momenta restricted by a cutoff Λ. We obtain a set of equations for additional terms in the \(Wb \bar t\) vertex and apply its solution to the process \(Z \to b\bar b\). We show that it is possible to obtain a consistent description of both deviations, which is quite nontrivial because these effects are not simply correlated. The necessary value of the anomalous W interaction coupling, λ=−0.22±0.01, is consistent with existing bounds and leads to definite predictions, e.g., for pair W production in e+e− collisions at LEP200.