| 1 | #!/usr/bin/env python
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| 2 |
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| 3 | import sys
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| 4 |
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| 5 | import ROOT
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| 6 |
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| 7 | if len(sys.argv) < 2:
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| 8 | print " Usage: Example1.py input_file"
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| 9 | sys.exit(1)
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| 10 |
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| 11 | ROOT.gSystem.Load("libDelphes")
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| 12 |
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| 13 | inputFile = sys.argv[1]
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| 14 |
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| 15 | # Create chain of root trees
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| 16 | chain = ROOT.TChain("Delphes")
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| 17 | chain.Add(inputFile)
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| 18 |
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| 19 | # Create object of class ExRootTreeReader
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| 20 | treeReader = ROOT.ExRootTreeReader(chain)
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| 21 | numberOfEntries = treeReader.GetEntries()
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| 22 |
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| 23 | # Get pointers to branches used in this analysis
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| 24 | branchJet = treeReader.UseBranch("Jet")
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| 25 | branchElectron = treeReader.UseBranch("Electron")
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| 26 |
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| 27 | # Book histograms
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| 28 | histJetPT = ROOT.TH1F("jet_pt", "jet P_{T}", 100, 0.0, 100.0)
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| 29 | histMass = ROOT.TH1F("mass", "M_{inv}(e_{1}, e_{2})", 100, 40.0, 140.0)
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| 30 |
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| 31 | # Loop over all events
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| 32 | for entry in range(0, numberOfEntries):
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| 33 | # Load selected branches with data from specified event
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| 34 | treeReader.ReadEntry(entry)
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| 35 |
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| 36 | # If event contains at least 1 jet
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| 37 | if branchJet.GetEntries() > 0:
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| 38 | # Take first jet
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| 39 | jet = branchJet.At(0)
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| 40 |
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| 41 | # Plot jet transverse momentum
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| 42 | histJetPT.Fill(jet.PT)
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| 43 |
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| 44 | # Print jet transverse momentum
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| 45 | print jet.PT
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| 46 |
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| 47 | # If event contains at least 2 electrons
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| 48 | if branchElectron.GetEntries() > 1:
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| 49 | # Take first two electrons
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| 50 | elec1 = branchElectron.At(0)
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| 51 | elec2 = branchElectron.At(1)
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| 52 |
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| 53 | # Plot their invariant mass
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| 54 | histMass.Fill(((elec1.P4()) + (elec2.P4())).M())
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| 55 |
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| 56 | # Show resulting histograms
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| 57 | histJetPT.Draw()
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| 58 | histMass.Draw()
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| 59 |
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| 60 | raw_input("Press Enter to continue...")
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