wiki:Frascati

Version 1 (modified by trac, 6 years ago) (diff)

--

QCD at the LHC, Frascati 2010

Two lectures are given on QCD at the LHC.

  1. Accurate QCD : Fixed order calculations from LO to NNLO
  2. Useful QCD : Parton Showers
  3. Best QCD : Merging FO calculations with PS at LO and NLO.

The PDF of the lectures can be found here.

The examples and exercises are related to physics at the LHC.

Basic aspects of QCD

Various Tests and exercises

A collection of test, exercises, and web applications on pQCD can be found in QCD-exercises.pdf.

Exercise on recursive relations

Think about the computation of q \bar q + n \gamma in a recursive way, by trying not calculate the same quantities twice. Show that the complexity of the calculation goes from n! (factorial) to 2{n-1} (exponential) .

Going NLO

  1. pp>H at LO (1-loop): details of the calculation (Mathematica Notebook) HiggsGG-LO-mtfinite.nb
  2. pp>H at NLO: details of the calculation (Mathematica Notebook) higgsGG-NLO.nb
  3. pp>H at NLO: cross section evaluation for the LHC (Mathematica Notebook+PDF libraries to be compiled) phenHiggs.tar.gz.

A summary of the results can be found in Higgs.pdf.

Selected exercises on QCD that can be solved with a Matrix Element generator.

  • [:DeadCone:Radiation from heavy quarks]: the dead cone in %$e^+e^- \to Q \bar Q g$%.
  • [:GluonSpin:Spin of the gluon]: Vector vs scalar in the angular correlations of %$ e^+ e^- \to$% 4 jets.
  • [:2Jets:Jets] : Di-jet kinematics and rates in pp collisions.
  • [:3Jets:3 Jets] : Energy distributions in 3-jet events in pp collisions.
  • [:tt:top production] : %$t \bar t$% production, Tevatron vs LHC.
  • [:WAsymm:Drell-Yan]: rapidity asymmetry at the Tevatron and LHC.
  • [:TopDecaySpinCorrelations: Spin correlations in top decay], by Bryan Webber.

Monte Carlo integration

A short introduction to the techniques of Monte Carlo integration. Exercises proposed during lecture are collected in this Mathematica Notebook: mc101.nb.

LHC Phenomenology

  • [:DiscoverTheHiggs:SM Higgs discovery at the LHC]: Three important channels
  • [:WarmingUpChallenge:Simple Black Boxes]: New gauge bosons

How to familiarize with Software.MadGraph

All exercises proposed can be "solved" or checked with Software.MadGraph / Software.MadEvent. Here is how to familiarize with the code.

  • Logon to the Software.MadGraph web site and register.
  • Familiarize with the code by generating a few processes in QED and QCD trying to guess which diagrams appear. What is the minimum number of jets have to be asked for in %$e^+e^-$% collisions so that the triple gauge vertex appear?
  • Look at the new physics models and check the particle and interactions content.
  • Generate events for a few selected processes and look at the plots:
    • ttbar production with decays: pp>tt~>bb~mu+e-ve~vm
    • VV production: pp>VV> leptons, with V=Z,W.
    • Single top + Higgs: pp>tHj (QCD=0, QED=3, j=gudsc,p=gudscb). Show that there is a large negative interference between the diagrams

-- Main.FabioMaltoni - 05 May 2010

Attachments