TEN YEARS OF PRECISION ELECTROWEAK PHYSICS

Abstract

This summer we mark the tenth anniversary of the beginning of a very important period in the study of the Standard Model (SM) [1] and some of its extensions. Namely, in August of 1989, LEP started operations at CERN. Approximately at the same time, SLC and the Mark II detector were switched on at SLAC, and FNAL began the precision studies of the W mass. There have also been important contributions from other great laboratories. A very attractive feature of this subject and period has been the detailed interplay between theory and experiment. On the experimental side, the accuracy often reaches 0.1% and sometimes it is much better, as in the measurement of the Z mass. On the theoretical side, the study of electroweak corrections to allowed processes, i.e. processes not forbidden in lowest order, has been the basis for the detailed comparisons currently achieved. Because the path to renormalization has been often reviewed, I will focus on certain aspects and applications of the theory that are closely connected with experiment. This subject is vast and my time limited, so that the topics and references are not intended to be exhaustive. In particular, apologies are due beforehand for the omission of many important contributions. From the beginning, in order to regularize ultraviolet divergences, most calculations in electroweak physics have been carried out in the dimensional regularization scheme [2]. The application of this approach to regularize infrared divergences and mass singularities was proposed and analyzed somewhat later [3]. In the seventies, radiative corrections to ,B and muon decays played an important role in the analysis of the universality of the weak interactions and its implications for the phenomenological viability of the SM [4]. The evaluation of the one-loop corrections to gμ 2 dates from that period, and there were also a number of important qualitative results, such as the absence of parity and strangeness violating corrections of 0(a) to strong interactions [5], the cancelation of ultraviolet divergences in natural relations [6], the discovery that heavy particles do not generally decouple in electroweak corrections and that a heavy top quark gives contributions of O(GN,m?) to the p parameter [7], and