The Discovery of the Weak Interaction

Abstract

All the known interactions that occur in nature can be reduced to four interactions between material particles. Listed in order of decreasing strength, these are: the strong (nuclear) interaction, electromagnetism, the weak (nuclear) interaction, and gravity (see Table 1.1). In contrast to the strong interaction, the weak interaction operates between all particles. It causes reactions which make these particles ultimately decay into the stable leptons and hadrons, that is, electrons, neutrinos, and protons. Characteristic in these reactions is the change in charge of the particles which undergo the reactions. The small strength of the weak interaction goes along with its small range. Unlike all other interactions, the weak interaction does not produce bound states, as do the strong interaction, which is responsible for the formation of atomic nuclei, the electromagnetic interaction, which binds together atoms and molecules, and gravity, which is the source of binding of objects on an astronomical scale. In order to better understand our modern theory of the weak interaction it is convenient to start with a short review of the history of its discovery.