2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/46574We review the empirical evidence for the validity of the Standard Electroweak Theory in nature. The experimental data are interpreted in terms of an effective Lagrangian for Z physics, allowing for potential sources of SU(2) violation and containing the predictions of the Standard Electroweak Theory as a special case. Particular emphasis is put on discriminating loop corrections due to fermion-loop vector-boson propagator corrections on the one hand, from corrections depending on the non-Abelian structure and the Higgs sector on the other hand. Results from recently obtained fits of the Higgs-boson mass are reported, yielding M_H < 550GeV [800GeV] at 95% C.L. based on the input of swbar^2(LEP+SLD)=0.23165+-0.00024 [swbar^2(LEP)=0.23200 +-0.00027]. With respect to LEP2, it is emphasized that first direct experimental evidence for non-zero non-Abelian couplings among the vector bosons can be obtained even with restricted e+e- luminosity.Talk presented at the International School of Subnuclear Physics, 34th Course: Effective Theories and Fundamental Interactions, Erice, Sicily, 3-12 July, 1996. 24 pages, latex, 10 ps and 2 eps files includedHigh Energy Physics - Phenomenologytext