Decoupling in QED and QCD

Abstract

Decoupling of a heavy flavour in QCD is discussed in a pedagogical way. First we consider a simpler case: decoupling of muons in QED. All calculations are done up to 2 loops.

Comments: Lecture at 5-th Helmholtz international summer school Calculations for modern and future colliders Dubna, July 23 -- August 2, 2012, 21 pages