Infrared and collinear dynamics in massless gauge theories

Abstract: I describe the treatment of mass divergences in perturbative massless gauge theories, their dynamical interpretation and some of their phenomenological consequences. A one-loop example is worked out in some detail, then some results and techniques valid to all orders in perturbation theory are briefly described. I introduce some of the tools necessary to prove factorization theorems, and show how they can be used also to resum certain classes of logarithmic contribution to all orders. Finally, I derive some implications on the all-order structure of mass divergences for amplitudes in non-abelian gauge theories, using the Sudakov form factor as an example.

Each lecture is intended to last last 1h30m plus 30m for questions and discussions.