ABSTRACT
This chapter describes the renormalization of the charge in QED. In QCD the strong coupling runs in the opposite way to QED, becoming smaller at large values of small distances – the property of asymptotic freedom. The result of Politzer and of Gross and Wilczek, when combined with the motivations for a colour SU(3) group, led rapidly to the general acceptance of QCD as the theory of strong interactions, a conclusion reinforced by the demonstration by Coleman and Gross that no theory without Yang-Mills fields possessed the property of asymptotic freedom. The chapter shows how QCD corrections to the simple parton model, calculated using RGE techniques, predict observable violations of scaling in deep inelastic scattering.
