First Evidence for Electroweak Radiative Corrections from the New Precision Data

The analysis of the newest data on the leptonic Z-decays and m W appears to reveal the first manifestations of electroweak radiative corrections. In fact, these data differ, at the level of 2σ, from their electroweak Born values, while they agree, to within 1σ, with the theoretical values which take the electroweak radiative corrections into account. Previous data were within 1σ in agreement with both sets of values. The traditional way of analyzing the data on electroweak radiative corrections , (see for instance [1]-[3]), is to not split off from them the large and purely electromagnetic effect of the running of the electric charge from q 2 = 0 to q 2 = m 2 Z. According to that approach, which starts from α ≡ α(0) = 1/137.0359895(61), the " electroweak " corrections appear to be large and to have been observed for a long time. By analyzing them, many authors [4] came already several years ago to the conclusion that the mass of the top quark must be close to 130 GeV or heavier. In a series of papers [5]-[9] we developed an approach in which the running of α(q 2) is explicitly excluded from the genuinely electroweak corrections and included in the electromagnetic ones. Our main argument is that the running of α(q 2) up to q 2 = m 2 Z is a purely electromagnetic phenomenon which is totally insensitive to the existence of electroweak bosons (W, Z and higgs), and that α(0), with all its impressive accuracy, is wholly irrelevant to electroweak physics even at low energy [10]. Our approach starts with the most accurately known electroweak observables: and has three free parameters: the top quark mass, m t , the Higgs boson mass, m H , and the QCD coupling constant ¯ α s ≡ α s (m Z). The conventional nature of the definition on ¯ α is analyzed in [14].