Tests for lecture 1

1. Explain the main differences between abelian and non abelian gauge theories (between QED and QCD).
2. What are the ingredients needed for a full NLO and NNLO computation?

Why is this needed?

1. Why can the cross-section for %$e^+e-\rightarrow hadrons$% be described by the partonic cross-section %$e^+e-\rightarrow q\bar q$%?
2. Explain the physical meaning of Bjoerken scaling.
3. What are the building blocks needed for a fully exclusice cross-section computation? Which of these building blocks can be calculated inside perturbative QCD?
4. What is the meaning of the renormalisation scale %$\mu_R$% and the factorisation scale %$\mu_F$%?
5. In experiments, we don't see free quarks and gluons (why?), but we see "sprays" of hadrons instead in the detector. Such "sprays" of particles are called jets. Using the formulas given on slide 50 of lecture 1, explain why it is meaningful to say that a parton (a quark or a gluon) will evolve into a jet.

-- Main.ClaudeDuhr - 02 Sep 2008