== Collider Event Generation ==
==== [http://www.phys.nthu.edu.tw/~numscc/nums-hep2011/ NumS-HEP 2011 school], NCTU, Taiwan, 17-23 Jan 2011 ====

=== Authors ===

   * Johan Alwall (lecturer)
=== Lectures ===

Find the pdf of the 3 x 1.5 hours lectures:

   * [attachment:NumS-HEP_lectures.pdf NumS-HEP_lectures.pdf]
=== References ===

   * [http://www.hep.phy.cam.ac.uk/theory/webber/QCDbook.html QCD and Collider Physics] by Keith Ellis, James Stirling, Bryan Webber (Cambridge Monographs, 1996).
   * [wiki:FurtherReading Perspectives on LHC physics, Ed. by G. Kane and A. Pierce].
   * [http://home.thep.lu.se/~torbjorn/pythia/lutp0613man2.pdf Pythia 6 Physics and Manual] (excellent introduction to event generation, parton showers and hadronization).
=== Basic exercises 1: Familiarize with Software.MadGraph ===

   * Logon to the Software.MadGraph web site and register: http://madgraph.hep.uiuc.edu.
   * Register with a valid e-mail address
   * Feynman diagrams. Generate a few processes (with different QED + QCD couplings) trying to guess which diagrams appear: 
      * uu~>tt~
      * gg>tt~
      * gg>tt~h (in SM and HEFT)
      * uu~>tt~bb~
   * Subprocess identification. List all subprocesses contributing to: 
      * pp>l+vljj
      * pp>tt~bb~
      * pp>tt~jj
   * Look at the new physics models and check the particle and interactions content.
   * Advanced: Download the MG/ME package and play with the standalone version.
=== Basic exercises 2: Calculate cross sections and generate events ===

   * Generate events for a few selected processes (work in groups, pick one each), for Tevatron and LHC energies. Does the cross section scale as you expect?
   * Compare cross sections with the processes of your neighbors. Do they differ as you would expect?
   * Look at the generated plots. Are the distributions as you would expect? Discuss with your neighbors.

Example processes:
   * ttbar production: pp > tt~, QED=0
   * W production: pp > l+vl
   * Z/gamma* production: pp > e+e-
   * g g > (H > e+ ve mu- vm~) (in HEFT model)
   * p p > (W+>e+ ve) (W- > mu- vm~) (important background to previous process)
=== Advanced exercises 1: The full simulation chain and advanced features ===

Try out the Analysis Tools:
   * a Fortran-based package: Software.MadAnalysis ([http://madgraph.phys.ucl.ac.be/cgi-bin/NewProcess/download.cgi Download it here])
   * a Root-based package: Software.ExRootAnalysis ([http://madgraph.hep.uiuc.edu/Downloads/ExRootAnalysis/ExRootAnalysis_V1.0.7.tar.gz Download it here])
   * a Mathematica-based package: [http://v1.jthaler.net/olympicswiki/doku.php?id=lhc_olympics:analysis_tools Chameleon]

Study SM Higgs production at the LHC. Choose a channel and investigate signal and background, using either of the packages above:
   1. The 2 lepton + missing Et final state: $ pp \to H\to W^+ W^- \to e^- \bar \nu_e \mu^+ \nu_\mu $
   1. 
      * Signal 
         * Events: [attachment:hww-signal.lhe.gz Parton Level] || [attachment:hww-signal.lhco.gz Detector Level]
         * Plots: [attachment:hww-signal-lhe.pdf Parton Level] || [attachment:hww-signal-lhco.pdf Detector Level]
      * Background 
         * Events: [attachment:hww-background.lhe.gz Parton Level] || [attachment:hww-background.lhco.gz Detector Level]
         * Plots: [attachment:hww-background-lhe.pdf Parton Level] || [attachment:hww-background-lhco.pdf Detector Level]
   1. Top associated production $pp \to t\bar tH$ with $H \to b \bar b$ 
      * Signal + Background samples: 
         * Events: attachment:ttbb.lhe.gz Parton Level] || [attachment:ttbb.lhco.gz Detector Level]
         * Plots: [attachment:ttbb-lhe.pdf Parton Level] || [attachment:ttbb-lhco.pdf Detector Level]
=== Advanced exercises 2: Implementation of a new model in MadGraph or [http://feynrules.phys.ucl.ac.be/ FeynRules] + MadGraph ===

Note that for these exercises you need to download the [http://madgraph.hep.uiuc.edu/Downloads/MG_ME_V4.4.56.tar.gz MadGraph/MadEvent package] (or [https://launchpad.net/madgraph5 MadGraph 5 package]) and work locally. You need a Fortran compiler (and for !MadGraph 5, Python v. 2.6 or 2.7).

For !FeynRules download and information, see the [http://feynrules.phys.ucl.ac.be/ FeynRules wiki]
   * Implement a (part of a) Standard Model extension into Software.MadGraph, specific for studying a given process. Generate events, study relevant distributions.
   * Determine most relevant Standard Model backgrounds with identical final states (“non-reducible”). If not too complicated, generate backgrounds with cuts determined from signal distributions.
   * Which other (“reducible”) backgrounds might be important?
   * Can the signal be seen at Tevatron? At the LHC?
==== Animations ====
   * [http://madgraph.hep.uiuc.edu/Event/ Interactive Flash version] Note you may want to zoom in!
   * [http://madgraph.hep.uiuc.edu/Event/fast_collisionx6.avi Fast movie (.avi) of collision]
   * [http://madgraph.hep.uiuc.edu/Event/collision.mov Guided movie (.mov) of collision]
   * [http://www.thedailyshow.com/watch/thu-april-30-2009/large-hadron-collider John Ellis on Daily Show]

-- Main.JohanAlwall - 2011-01-17