The theory of weak interactions in particle physics

We commence with a summary of the major theoretical ideas which have dominated the field of weak interactions during the last seven years. The main body of the review assumes that the Hamiltonian responsible for weak interactions has the traditional CP-invariant current-current form and that it is a good approximation to work to first order in the weak coupling constant; we then make a quantitative comparison of the resulting theoretical predictions with the experimental data. In the main we find widespread consistency, although the theory lacks predictive power in certain areas where the data seems to be quite simple. The serious inadequacies of the theory are exposed when we consider higher-order terms in the perturbation series; the theory predicts that these diverge unrenormalizably while the data indicates that they are very small. Finally, we review the experimental data on CP-invariant processes and discuss the models which have been advanced to explain this phenomenon.