Refined analysis of the electroweak precision data Original Research Article

We refine our recent analysis of the electroweak precision data at the Z0 pole by including the hadronic decay modes of the Z0. Within the framework of an effective Lagrangian we parametrize SU(2) violation by the additional process-specific parameters Δyν, Δyh, and Δyb (for the image, image, and image vertices) together with the previously introduced parameters Δx, Δy, and ɛ. We find that a six-parameter analysis of the experimental data is indeed feasible, and it is carried out in addition to a four-parameter fit for Δx, Δy, ɛ, and Δyb only. We re-emphasize that the experimental data have become sensitive to the (combined) magnitude of the vertex corrections at the image (image) and image vertices, Δy, which is insensitive to the notion of the Higgs mechanism but dependent on the non-Abelian, trifinear vector-boson coupling. Full explicit analytical results for the standard one-loop predictions for the above-mentioned parameters are given, and the leading two-loop top-quark effects are included. The analytic formulae for the analysis of the experimental data in terms of the parameters Δx, Δy etc. are presented in order to encourage experimentalists to persue such an analysis by themselves with future data.