Some aspects of weak interaction theory

Siebren Gerrit van der Wal

Research output: ThesisThesis fully internal (DIV)

Abstract

In this investigation we discuss two different aspects of weak interaction theory. The results of weak interaction experiments are described in a current-current picture to lowest order. From a fundamental point of view, such a description entails many problems. It is interesting to observe whether aspects of these difficulties can be studied within models which retain the basic features, while at the same time being, sufficiently simple to trace the implications of certain relevant assumptions. In the first part we study the underlying structure of the Feinberg-Pais approach of peratization. This approach aims to include higher order terms in the weak, interaction matrix element. We point out that the parameter independent Feinberg-Pais results are obtained by an analytic continuation to the value zero of a regularizing parameter. In sect 2 of part 1 we describe the context within which we calculate explicitly such a limit transition. We explicitly show that the imaginary part of the amplitude vanishes after the analytic continuation has been carried out. In sect 3 and 4 we analyze this phenomenon in detail and we point out that major physical objections exist against the result. The main conclusions have been summarized in sect 6. The peratization scheme of Feinberg and Pais turns out to be highly questionable. In part 2 we discuss the weak decay of mesons within the quark model. This physical model suggests to ascribe the interaction between hadrons and leptons the interaction between leptons and elementary quark constituents. We describe the bound states by means of relativistic Bethe-Salpeter amplitude The description of the general current matrix elements is given in chapter 1. It appears that this approach leads to an interesting symmetry relation for the current matrix elements. We concentrate on the information that can be obtained from this symmetry relation together with the requirement of normalization of the BetheSalpeter amplitudes of the pseudoscalar octet mesons. In chapter 2 we compare various approaches for normalizing the Bethe-Salpeter amplitude. In chapter 3 we discuss the K l2 and K l3 decay within the quark model. We derive the Ademollo-Gatto theorem and comment on a pattern which gives the Callan-Treiman relation.
Original languageEnglish
QualificationDoctor of Philosophy
Supervisors/Advisors
  • Tolhoek, H, Supervisor
Publisher
Publication statusPublished - 1971

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