ABSTRACT
The electroweak theory of Glashow, Salam and Weinberg, now recognized as one of the pillars of the Standard Model, was formulated long before such precision measurements existed, under the impetus of quite compelling theoretical arguments. These had to do, mainly, with certain inprinciple difficulties associated with the current–current model, if viewed as a ‘theory’. This chapter investigates whether the IVB model can do any better with unitarity than the current–current model. The unitarity-violating processes turn out to be those involving external particles. The objection is perfectly valid, and the chapter describes it by linking high-energy behaviour to the problem of renormalizability, rather than unitarity. It is surely remarkable how the quantum fluctuations of a yet-to-be-detected new particle could pin down its mass so precisely. It seems hard to deny that Nature has indeed made use of the subtle intricacies of a spontaneously broken non-Abelian gauge theory.
