CHAPTER 21 - Standard model of the electroweak interaction

Abstract

This chapter describes the standard unified model of electroweak interactions and explains the model lagrangian containing the vector and scalar fields, and the fields of the electron and electron neutrino as representatives of fermions. It discusses the addition of other leptons and quarks. The chapter highlights the relationship between the masses of certain intermediate bosons, the fine structure constant α, and the Fermi constant G . To construct a renormalizable theory of weak interactions, photons and intermediate bosons should be introduced on an equal basis—as gauge fields— and masses should be given spontaneously to intermediate bosons leaving the photon massless. The standard model is based on the local SU(2) × U(1) symmetry corresponding to four gauge fields—two of them are charged and two are neutral. In a certain sense, the isotopic group has a more reflective physical meaning than the usual isotopic invariance of strong interactions, because weak isotopic charges are sources of vector particles. Addition of quarks to the standard model is done in a manner where the left-handed particles form isodoublets and the right-handed ones form isosinglets.