DO PRESENT LEP DATA PROVIDE EVIDENCE FOR ELECTROWEAK CORRECTIONS?

Abstract

The Born approximation, based on [Formula: see text] instead of α, reproduces all electroweak precision measurements within their (1σ) accuracy. The low upper limits for the genuinely electroweak corrections constitute one of the major achievements of LEP. The astonishing smallness of these corrections results from the cancellation of a large positive contribution from the heavy top quark and large negative contributions from all other virtual particles. It is precisely the non-observation of electroweak radiative corrections that places stringent upper and lower limits on the top mass.