Gauge theories of weak interaction
Martinus J. G. Veltman · Utrecht University Repository (Utrecht University) · 1980
The purpose of these notes is to produce an introduction to the presently popular standard model of weak and electromagnetic interactions. This model has a number of ingredients, leptons, quarks. vector bosom, photons and finally also Higgs scalars, and of these only the leptons and photons are directly observed particles. The evidence for quarks comes from another domain of physics, namely strong interactions supposedly described by quantum chromodynamics. The massive vector bosons as well as the Higgs particles are theoretical imventions, and while few people doubt the existence of vector bosons, many are sceptical with respect to the Higgs system. Meanwhile, theorists have gone beyond the standard model, and speculations on possible grand unified schemes have emerged. AlSO there are speculations on the possible compositeness of quarks and leptons. or Higgs particles. In these notes we will not discuss grand unified theories, and the question of physics beyond 1 TeV (where compositeness may show up) will be touched upon only sketchily. Our metric is such that k2 < 0 if k is a timelike vector.