Electroweak Processes Beyond the Tree Approximation

Abstract

This set of three lectures is intended to push further at a more advanced level the study of electroweak processes which was started in the parallel courses of Drs. Ecker and Wagner. Much work has been devoted recently to a careful analysis of the higher order corrections to the tree diagram relations on which the experimental tests of the standard model of electroweak interactions are based. The subject seems by now mature for a clear and reasonably compact presentation of methods and results. I shall devote the first part of these lectures to expose in a simple and systematic way how the most important terms in the corrections to the electroweak processes and parameters (sin ²θ_W, M_W, M_Z, and so on) arise and can be evaluated. This will lead us into a discussion of leptonic and semileptonic electroweak processes in the formalism of operator expansion and renormalization group methods. The connection with the theory of non—leptonic weak processes is naturally introduced by the close similarity of approach and by the structure of the operator mixings among some semileptonic and non-leptonic amplitudes.

Lectures given at the XXI. Internationale Universitätswochen für Kernphysik, Schladming, Austria, February 25–March 6,1982