ABSTRACT
This chapter discusses some elementary characteristics of nuclear beta decay. Within a set of isobaric nuclei, beta decay occurs if there is a neighbouring nucleus with smaller mass. The energy dependence of the phase-space integral generally becomes stronger as the number of particles participating in the interaction increases. The chapter describes the classical theory of weak interaction, based on Fermi's theory of 1934, and also touch on its historical development. The classical theory, in which the exchange bosons of the modern Glashow–Weinberg–Salam theory were unknown, is not simply of historical interest; its description of the classical low-energy weak processes, such as ß decay or µ decay, gives the same results as the modern theory. The chapter considers other weak processes alongside nuclear beta decay. It also describes the relationship between the current–current interaction and the nuclear structure matrix elements in ß decay.
