| | 43 | == MadGraph and Pheno Exercises == |
| | 44 | A summary of advanced QCD and pheno exercises can be found [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Copenhagen2010/exercises-NBI.pdf here]. |
| | 45 | === Tutorial 1: Familiarize with MadGraph === |
| | 46 | * Logon to the MadGraph web site and register: http://madgraph.hep.uiuc.edu. |
| | 47 | * Register with a valid e-mail address |
| | 48 | * Feynman diagrams. Generate a few processes (with different QED + QCD couplings) trying to guess which diagrams appear: |
| | 49 | * uu~>tt~ |
| | 50 | * gg>tt~ |
| | 51 | * gg>tt~h |
| | 52 | * uu~>tt~bb~ |
| | 53 | * Subprocess identification. List all subprocesses contributing to: |
| | 54 | * pp>h>tt~bb~ |
| | 55 | * pp>tt~bb~ |
| | 56 | * pp>tt~jj |
| | 57 | * Look at the new physics models and check the particle and interactions content. |
| | 58 | * Advanced: Download the MG/ME package and play with the standalone version. |
| | 59 | * [http://cp3wks05.fynu.ucl.ac.be/twiki/bin/view/Physics/SimpleKinematics Kinematics at the LHC]: refresh the kinematics of an hadron collider. |
| | 60 | === Tutorial 2: Calculate cross sections and generate events === |
| | 61 | |
| | 62 | Generate events for a few selected processes and look at the plots: |
| | 63 | |
| | 64 | * ttbar production with decays: p p > t t~, t > b mu+ vm , t~ > b~ e- ve~ |
| | 65 | * VV production: pp>VV> leptons, with V=Z,W. |
| | 66 | * Single top + Higgs: pp>tHj (QCD=0, QED=3, j=gudsc,p=gudscb). Show that there is a large negative interference between the diagrams. |
| | 67 | * gg>H>WW |
| | 68 | * Weak boson fusion |
| | 69 | |
| | 70 | Some phenomenological applications (at the parton level): |
| | 71 | |
| | 72 | * [http://cp3wks05.fynu.ucl.ac.be/twiki/bin/view/Physics/2Jets Jets] : Di-jet kinematics and rates in pp collisions. |
| | 73 | * [http://cp3wks05.fynu.ucl.ac.be/twiki/bin/view/Physics/3Jets 3 Jets] : Energy distributions in 3-jet events. |
| | 74 | * [http://cp3wks05.fynu.ucl.ac.be/twiki/bin/view/Physics/WAsymm Drell-Yan] : Study the rapidity asymmetry at the Tevatron. |
| | 75 | * [http://cp3wks05.fynu.ucl.ac.be/twiki/bin/view/Physics/tt top production] : $t \bar t$ production, Tevatron vs LHC. |
| | 76 | * [http://cp3wks05.fynu.ucl.ac.be/twiki/bin/view/Physics/tprime t' production] : $t'$ production at the LHC. |
| | 77 | === Tutorial 3: The full simulation chain and advanced features === |
| | 78 | |
| | 79 | Try out the Analysis Tools: |
| | 80 | * a Fortran-based package: MadAnalysis ([http://madgraph.phys.ucl.ac.be/cgi-bin/NewProcess/download.cgi Download it here]) |
| | 81 | |
| | 82 | Study what is known of a SM Higgs at the LHC: |
| | 83 | * Find the best prediction for Higgs production at the LHC [http://maltoni.web.cern.ch/maltoni/TeV4LHC/index.html here]. |
| | 84 | * Find the Higgs branching ratios [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/CernSummerSchool08/h-br.pdf here]. |
| | 85 | Choose a channel and investigate signal and background: |
| | 86 | 1. The 2 lepton + missing Et final state: $pp \to H\to W^+ W^- \to e^- \bar \nu_e \mu^+ \nu_\mu$ |
| | 87 | * Signal |
| | 88 | * Events: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-signal.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-signal.lhco.gz Detector Level] |
| | 89 | * Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-signal-lhe.pdf Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-signal-lhco.pdf Detector Level] |
| | 90 | * Background |
| | 91 | * Events: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-background.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-background.lhco.gz][Detector Level] |
| | 92 | * Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-background-lhe.pdf Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/hww-background-lhco.pdf Detector Level] |
| | 93 | 2. Top associated production $pp \to t\bar tH$ with $H \to b \bar b$ |
| | 94 | * Signal + Background samples: |
| | 95 | * Events: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/ttbb.lhe.gz Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/ttbb.lhco.gz Detector Level] |
| | 96 | * Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/ttbb-lhe.pdf Parton Level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/DiscoverTheHiggs/ttbb-lhco.pdf Detector Level] |
| | 97 | |
| | 98 | === Tutorial 4: The MadGraph BlackBox Challenge === |
| | 99 | |
| | 100 | Three "black boxes" are given, in the form of event files in the LHC Olympics format and a series of selected plots: |
| | 101 | |
| | 102 | * Box A : [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Milano2010/A.lhco.gz Events] Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Milano2010/A-lhe.pdf Parton level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Milano2010/A.pdf Detector level] |
| | 103 | * Box B : [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Milano2010/B.lhco.gz Events] Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Milano2010/B-lhe.pdf Parton level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Milano2010/B.pdf Detector level] |
| | 104 | * Box C : [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Milano2010/C.lhco.gz Events] Plots: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Milano2010/C-lhe.pdf Parton level] [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Milano2010/C.pdf Detector level] |
| | 105 | |
| | 106 | 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: |
| | 107 | |
| | 108 | * Model 1 : Extra Z (zp) : What its mass? Does it have Standard Model couplings to fermions? |
| | 109 | * Model 2 : Heavy Scalar (h): What its mass? Is it a SM Higgs? |
| | 110 | * Model 3 : Extra W (wp+ or wp-) : What its mass? Does it have Standard Model couplings to fermions? |
| | 111 | |
| | 112 | Useful extra information: |
| | 113 | * In the plots $H_T=\sum |p_T^{vis}| + E_T^{miss}$. |
| | 114 | * 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-. |
| | 115 | * 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. |
| | 116 | * 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. |
| | 117 | |
| | 118 | === Monte Carlo's === |
| | 119 | |
| | 120 | For those interested in getting deeper into Monte Carlo techniques, here are some more exercises: |
| | 121 | |
| | 122 | * Write the simplest integration function based on the definition of average and error |
| | 123 | * Importance sampling via an analytic transformation |
| | 124 | * Von Neumann's rejection method : plain and improved |
| | 125 | * Phase space for 1 -> n particles |
| | 126 | * Vegas |
| | 127 | * Top decay : comparison among the various methods |
| | 128 | * qq -> tt production |
| | 129 | |
| | 130 | All exercises are presented and solved this Mathematica Notebook: [http://cp3wks05.fynu.ucl.ac.be/twiki/pub/Physics/Copenhagen2010//mc101.nb mc101.nb]. Reference: [http://www.slac.stanford.edu/spires/find/hep/www?eprint=hep-ph/0006269 Introduction to MC methods], by [http://wwwthep.physik.uni-mainz.de/~stefanw/ Stefan Weinzierl] |
| | 131 | === Animations === |
| | 132 | * [http://madgraph.hep.uiuc.edu/Event/ Interactive Flash version] Note you may want to zoom in! |
| | 133 | * [http://madgraph.hep.uiuc.edu/Event/fast_collisionx6.avi Fast movie (.avi) of collision] |
| | 134 | * [http://madgraph.hep.uiuc.edu/Event/collision.mov Guided movie (.mov) of collision] |
| | 135 | * [http://www.thedailyshow.com/watch/thu-april-30-2009/large-hadron-collider John Ellis on Daily Show] |
