wiki:HEPTOOLS08

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HEPTOOLS 2008 <BR> Graduate School in Physics at Colliders : <BR> "From twistors to Monte Carlos"

Lectures

Find here the pdf of the 4 hour lecture on "Monte Carlo's for the LHC" by Fabio Maltoni.<br> Find here a very nice course on QCD and MC by Stefano Frixione.

MC101

A short introduction to the techniques of Monte Carlo integration. Exercises include:

  • Write the simplest integration function based on the definition of average and error
  • Importance sampling via an analytic transformation
  • Von Neumann's rejection method : plain and improved
  • Phase space for 1 -> n particles
  • Vegas
  • Top decay : comparison among the various methods
  • qq -> tt production

All exercises are presented and solved this Mathematica Notebook: mc101.nb. Reference: Introduction to MC methods, by Stefan Weinzierl

Exercises

All exercises proposed here can be "solved" or checked with Software.MadGraph / Software.MadEvent. To familiarize with the code click [:MGFamiliarize:here].

  • [: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$% 4 jets.
  • [:2Jets:Jets] : Di-jet kinematics and rates in pp collisions.
  • [:3Jets:3 Jets] : Energy distributions in 3-jet events.
  • [:TopDecaySpinCorrelations: Spin correlations in top decay].
  • [:tt:top production] : %$t \bar t$% production, Tevatron vs LHC.
  • [:SimpleKinematics:Kinematics at the LHC]: single particle quantities.

Reference: QCD and Collider Physics

by Keith Ellis, James Stirling, Bryan Webber (Cambridge Monographs, 1996).

Discover the SM Higgs at the LHC

  • Find the best prediction for Higgs production at the LHC here.
  • Find the Higgs branching ratios here.

Choose a channel and investigate signal and background:

  1. The 4 lepton final state: %$pp \to H\to Z Z \to e^+e^- \mu^+ \mu^-$%

<!-- * Plots: Parton Level Detector Level -->

<!-- * Plots: Parton Level Detector Level -->

  1. The 2 lepton + missing Et final state: %$pp \to H\to W^+ W^- \to e^- \bar \nu_e \mu^+ \nu_\mu $%

<!-- * Plots: Parton Level Detector Level -->

<!-- * Plots: Parton Level Detector Level -->

  1. Top associated production %$pp \to t\bar tH$% with %$H \to b \bar b$%

Discover New gauge bosons at the LHC

Three "black boxes" are given, in the form of event files in the LHC Olympics format and a series of selected plots:

Black boxes contain only signal events. The students are asked to pair up the boxes above with the following models and also answer to the questions:

  • Model 1 : Extra Z (zp) : What its mass? Does it have Standard Model couplings to fermions?
  • Model 2 : Heavy Scalar (h): What its mass? Is it a SM Higgs?
  • Model 3 : Extra W (wp+ or wp-) : What its mass? Does it have Standard Model couplings to fermions?

Useful extra information:

  • In the plots %$H_T=\sum ||p_T^{vis}|| + E_T^{miss}$%.
  • A SM-like Z' would decay (more or less democratically) into: jet jet (uu~,cc~,dd~,ss~,bb~), t tbar (tt~), lept+lept- (e+e-,mu+mu-,ta+ta-), neutrino anti-neutrino (ve ve~,vm vm~,vt vt~). It could also have couplings to SM W and Z, and in that case would decay in to ZZ and W+W-.
  • An Higgs couple to particles with a strength which is proportional to the particle masses. A SM-like heavy H would decay in to t tbar (tt~), W+W-, ZZ.
  • A SM-like W'+ would decay into: jet jet (ud~,cs~), t b (tb~), lept neutrino (e+ ve , mu+ vm, ta+ vt). It could also have couplings to SM W and Z, and in that case would decay in to ZW.

Analysis Tools

-- Main.FabioMaltoni - 03 Jan 2008

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