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CMS_2013_I1208923

Jet-pT and dijet mass at sqrt(s) = 7 TeV
Experiment: CMS (LHC)
Inspire ID: 1208923
Status: VALIDATED
Authors:
  • Markus Radziej
  • Samatha Dooling
No references listed
Beams: p+ p+
Beam energies: (3500.0, 3500.0) GeV
Run details:
  • Hard QCD process with a flat pT spectrum is recommended.

The single jet differential cross section has been measured as a function of the jet momentum and the dijet differential cross section as a function of the dijet mass. The data has been recorded by the CMS detector at the center of mass energy of 7 TeV. To reconstruct the jets, the anti-$k_T$ algorithm with a cone radius of $R = 0.7$ (AK7) has been used. The results are split into five rapidity bins, ranging from 0.0 to 2.5 with a width of 0.5 each.

Source code: CMS_2013_I1208923.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4#include "Rivet/Projections/FastJets.hh"
 5
 6namespace Rivet {
 7
 8  // This analysis is a derived from the class Analysis:
 9  class CMS_2013_I1208923 : public Analysis {
10
11  public:
12
13    // Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2013_I1208923);
15
16    // Book histograms and initialize projections:
17    void init() {
18      const FinalState fs;
19      declare(fs, "FS");
20
21      // Initialize the projections
22      declare(FastJets(fs, JetAlg::ANTIKT, 0.7), "Jets");
23
24      // Book histograms
25      book(_h_sigma, {0., 0.5, 1., 1.5, 2., 2.5},
26                     {"d01-x01-y01", "d01-x01-y02", "d01-x01-y03", "d01-x01-y04", "d01-x01-y05"});
27      book(_h_invMass, {0., 0.5, 1., 1.5, 2., 2.5},
28                       {"d02-x01-y01", "d02-x01-y02", "d02-x01-y03", "d02-x01-y04", "d02-x01-y05"});
29
30    }
31
32    // Analysis
33    void analyze(const Event &event) {
34
35      const FastJets &fJets = apply<FastJets>(event, "Jets");
36
37      // Fill the jet pT spectra
38      const Jets& jets = fJets.jetsByPt(Cuts::pt>100.*GeV && Cuts::absrap <2.5);
39      for (const Jet& j : jets) {
40        _h_sigma->fill(fabs(j.rapidity()), j.pT() / GeV);
41      }
42
43      // Require two jets
44      const Jets& dijets = fJets.jetsByPt(Cuts::pt>30.*GeV && Cuts::absrap < 2.5);
45      if (dijets.size() > 1) {
46        if (dijets[0].momentum().pT() / GeV > 60.) {
47          // Fill the invariant mass histogram
48          double ymax = max(dijets[0].momentum().absrapidity(), dijets[1].momentum().absrapidity());
49          double invMass = FourMomentum(dijets[0].momentum() + dijets[1].momentum()).mass();
50          _h_invMass->fill(fabs(ymax), invMass);
51        }
52      }
53
54    }
55
56
57    // Scale histograms by the production cross section
58    void finalize() {
59      scale(_h_sigma,   crossSection()/picobarn / sumOfWeights() / 2.0);
60      scale(_h_invMass, crossSection()/picobarn / sumOfWeights() / 2.0);
61      divByGroupWidth({_h_sigma, _h_invMass});
62    }
63
64  private:
65
66    Histo1DGroupPtr _h_sigma;
67    Histo1DGroupPtr _h_invMass;
68
69  };
70
71  RIVET_DECLARE_PLUGIN(CMS_2013_I1208923);
72}