Quantum Field Theory 3

This course is an introduction to renormalisation. The syllabus is

• • Loop diagrams and divergences

  • Renormalisation of QED and QCD

  • Asymptotic freedom

We'll start by finding the lagrangian for a U(1) abelian gauge theory, like QED, and for a nonabelian gauge theory like QCD. Then we'll consider what happens when you evaluate loop diagrams, and learn how to deal with the UV infinities which arise. This means doing regularisation and renormalisation. We'll look at the renormalisation of QED and QCD and see how this leads to asymptotic freedom for a nonabelian gauge theory like QCD. We'll also consider how to treat IR divergences, which arise from low-momentum regions of integration.

Learning material