ABSTRACT
The standard model is based on a gauge symmetry, which is what we have discussed in Ch. 12, Ch. 16 and Ch. 17. This symmetry governs the dynamics of the model. However, there are many other symmetries, or near-symmetries, in particle interactions, some of which we have discussed in earlier chapters in the book. Such symmetries are often very helpful in understanding various properties of hadrons and leptons. In this chapter, we discuss how some of these symmetries can be understood from the standard model Lagrangian.
