[66b590f] | 1 | Quick start with Delphes
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| 2 | ========================
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| 3 |
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| 4 | 1) Compile:
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| 5 |
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| 6 | make
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| 7 |
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| 8 | 2) Simulate p p -> b b~ events
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| 9 |
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[5babc8b] | 10 | tar xzvf pp2pp.hep.tgz
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[66b590f] | 11 | ./DelphesSTDHEP examples/delphes_card_prelLHCb.tcl delphes_output.root pp2bb.hep
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| 12 |
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| 13 |
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| 14 | For more details, please visit:
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| 15 |
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| 16 | https://cp3.irmp.ucl.ac.be/projects/delphes
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| 17 |
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| 18 |
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| 19 | Delphes 4 LHCb
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| 20 | ==============
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| 21 |
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| 22 | The card "delphes_card_prelLHCb.tcl" contains a preliminary parametrization of the LHCb detector.
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| 23 |
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| 24 | - ParticlePropagator
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| 25 |
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| 26 | particles are propagated in a constant B field.
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| 27 |
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| 28 | - ChargedHadronMomentumSmearing/ElectronEnergySmearing/MuonMomentumSmearing
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| 29 |
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| 30 | charged particles momenta are smeared according to detector resolution
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| 31 |
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| 32 | - TrackMerger
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| 33 |
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| 34 | charged particles are merged into single collection for simpler future processing
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| 35 |
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| 36 | - ImpactParameterSmearing
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| 37 |
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| 38 | charged particles transverse IP are smeared according to known LHCb tracking
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| 39 | performance.
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| 40 |
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| 41 |
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| 42 | - IdentificationMap
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| 43 |
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| 44 | This module is a recent addition in order to map particle misindentification rates
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| 45 | and reconstruction efficiencies.
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| 46 |
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| 47 | An example is given in the card but can be expanded if needed.
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| 48 |
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| 49 | - ECAL/HCAL
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| 50 |
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| 51 | Calorimeter modules are used to parametrize the energy response and angular
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| 52 | resolution of neutral objects such as photons/neutral hadrons.
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| 53 |
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| 54 | - TreeWriter
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| 55 |
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| 56 | user specifies here which collections are stored in the output.
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| 57 | By default tracks, neutral hadrons and photons are stored in this card.
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| 58 | Tracks contain muons, electrons, and charged hadrons.
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| 59 |
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| 60 |
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| 61 | Simple analysis using TTree::Draw
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| 62 | =================================
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| 63 |
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| 64 | Now we can start ROOT and look at the data stored in the output ROOT file.
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| 65 |
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| 66 | Start ROOT and load Delphes shared library:
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| 67 |
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| 68 | root -l
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| 69 | gSystem->Load("libDelphes");
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| 70 |
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| 71 | Open ROOT file and do some basic analysis using Draw or TBrowser:
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| 72 |
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| 73 | TFile::Open("delphes_output.root");
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| 74 | Delphes->Draw("Track.PT");
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| 75 | TBrowser browser;
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| 76 |
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| 77 | Note 1: Delphes - tree name, it can be learned e.g. from TBrowser
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| 78 |
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| 79 | Note 2: Track - branch name; PT - variable (leaf) of this branch
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| 80 |
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| 81 | Complete description of all branches can be found in
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| 82 |
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| 83 | doc/RootTreeDescription.html
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| 84 |
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| 85 | This information is also available at
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| 86 |
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| 87 | https://cp3.irmp.ucl.ac.be/projects/delphes/wiki/WorkBook/RootTreeDescription
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| 88 |
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| 89 |
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| 90 | Macro-based analysis
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| 91 | ====================
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| 92 |
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| 93 | Analysis macro consists of histogram booking, event loop (histogram filling),
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| 94 | histogram display.
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| 95 |
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| 96 | Start ROOT and load Delphes shared library:
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| 97 |
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| 98 | root -l
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| 99 | gSystem->Load("libDelphes");
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| 100 |
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| 101 | Basic analysis macro:
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| 102 |
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| 103 | {
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| 104 | // Create chain of root trees
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| 105 | TChain chain("Delphes");
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| 106 | chain.Add("delphes_output.root");
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| 107 |
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| 108 | // Create object of class ExRootTreeReader
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| 109 | ExRootTreeReader *treeReader = new ExRootTreeReader(&chain);
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| 110 | Long64_t numberOfEntries = treeReader->GetEntries();
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| 111 |
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| 112 | // Get pointers to branches used in this analysis
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| 113 | TClonesArray *branchTrack = treeReader->UseBranch("Track");
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| 114 |
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| 115 | // Book histograms
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| 116 | TH1 *histTrackPT = new TH1F("track pt", "track P_{T}", 50, 0.0, 20.0);
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| 117 |
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| 118 | // Loop over all events
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| 119 | for(Int_t entry = 0; entry < numberOfEntries; ++entry)
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| 120 | {
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| 121 |
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| 122 | // Load selected branches with data from specified event
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| 123 | treeReader->ReadEntry(entry);
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| 124 |
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[5babc8b] | 125 | // If event contains at least 1 track
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[66b590f] | 126 | if(branchTrack->GetEntries() > 0)
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| 127 | {
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[5babc8b] | 128 | // Take first track
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[66b590f] | 129 | Track *track = (Track*) branchTrack->At(0);
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| 130 |
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| 131 | // Plot track transverse momentum
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| 132 | histTrackPT->Fill(track->PT);
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| 133 |
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[5babc8b] | 134 | // Print electron transverse momentum and Particle Data Group ID
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| 135 | cout << track->PID<< " " << track->PT << endl;
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[66b590f] | 136 | }
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| 137 |
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| 138 | }
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| 139 |
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| 140 | // Show resulting histograms
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[5babc8b] | 141 | histTrackPT->Draw();
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[66b590f] | 142 | }
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| 143 |
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| 144 |
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| 145 | More advanced macro-based analysis
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| 146 | ==================================
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| 147 |
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| 148 | The 'examples' directory contains ROOT macros Example1.C, Example2.C and Example3.C.
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| 149 |
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| 150 | Here are the commands to run these ROOT macros:
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| 151 |
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| 152 | root -l
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| 153 | .X examples/Example1.C("delphes_output.root");
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| 154 |
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| 155 | or
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| 156 |
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| 157 | root -l examples/Example1.C\(\"delphes_output.root\"\)
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