ABSTRACT
The spectacular success of quantum electrodynamics in calculating the Lamb shift and the anomalous magnetic moment of the electron and muon, for example, stimulated many attempts to develop a quantum field theory of weak interactions. After all, low energy weak processes are characterised by the Fermi weak coupling constant. The only known method of breaking the local gauge invariance while maintaining renormalisability is to do so ‘spontaneously’. This requires the introduction of a scalar field which has a non-zero vacuum expectation value and which transforms non-trivially under the action of the group. This chapter derives the Feynman rules for the vertices involving two gauge particles and two scalars. It introduces seven independent parameters into the electroweak theory, where six of the seven parameters are completely determined without any direct recourse to weak interaction data.
