ABSTRACT
In this chapter, the authors describe the basic features of gauge theories and thus to prepare the way for the their discussion of the Glashow–Weinberg–Salam theory of the weak interaction. The idea behind gauge theories is based on the fact that both in quantum mechanics and in classical physics there exist quantities which it is in principle impossible to measure. Equivalent theories, which give the same predictions for all experiments, result for different values of these quantities. The authors discuss the mechanism of spontaneous symmetry breaking. This may be used to obtain massive gauge bosons, and to explain the different characteristics of electrons and neutrinos. The authors also discuss the Glashow–Weinberg–Salam (GWS) model, different algebraic condition is that the sum of all electric charges of the elementary fermions must vanish. Global internal symmetries may be divided into discrete and continuous symmetries.
