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CMS_2011_S8950903

Dijet azimuthal decorrelations in $pp$ collisions at $\sqrt{s} = 7$ TeV
Experiment: CMS (LHC)
Inspire ID: 885663
Status: VALIDATED
Authors:
  • Tomo Umer
References:
  • Phys. Rev. Lett. 106 (2011) 122003
  • arXiv: 1101.5029
Beams: p+ p+
Beam energies: (3500.0, 3500.0) GeV
Run details:
  • Inclusive QCD at $\sqrt{s} = 7 \text{TeV}$, $\hat{p_\perp} (or equivalent) greater than 20 GeV

Measurements of dijet azimuthal decorrelations in $pp$ collisions at $\sqrt{s} = 7$ TeV using the CMS detector at the CERN LHC are presented. The analysis is based on an inclusive dijet event sample corresponding to an integrated luminosity of 2.9/pb. Jets are anti-$k_t$ with $R = 0.5$, $p_\perp > 80 (30)$ GeV and $|\eta| < 1.1$.

Source code: CMS_2011_S8950903.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Tools/BinnedHistogram.hh"
 4#include "Rivet/Projections/FinalState.hh"
 5#include "Rivet/Projections/FastJets.hh"
 6
 7namespace Rivet {
 8
 9  /// CMS azimuthal decorrelations
10  class CMS_2011_S8950903 : public Analysis {
11  public:
12
13    RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2011_S8950903);
14
15
16    void init() {
17      FinalState fs;
18      FastJets akt(fs, FastJets::ANTIKT, 0.5);
19      declare(akt, "antikT");
20
21      {Histo1DPtr tmp; _h_deltaPhi.add( 80.,  110., book(tmp, 1, 1, 1));}
22      {Histo1DPtr tmp; _h_deltaPhi.add(110.,  140., book(tmp, 2, 1, 1));}
23      {Histo1DPtr tmp; _h_deltaPhi.add(140.,  200., book(tmp, 3, 1, 1));}
24      {Histo1DPtr tmp; _h_deltaPhi.add(200.,  300., book(tmp, 4, 1, 1));}
25      {Histo1DPtr tmp; _h_deltaPhi.add(300., 7000., book(tmp, 5, 1, 1));}
26    }
27
28
29    void analyze(const Event & event) {
30      const double weight = 1.0;
31
32      const Jets& jets = apply<JetAlg>(event, "antikT").jetsByPt();
33      if (jets.size() < 2) vetoEvent;
34
35      if (fabs(jets[0].eta()) > 1.1 || jets[0].pT() < 80.) vetoEvent;
36      if (fabs(jets[1].eta()) > 1.1 || jets[1].pT() < 30.) vetoEvent;
37
38      double dphi = deltaPhi(jets[0].momentum(), jets[1].phi());
39
40      _h_deltaPhi.fill(jets[0].pT(), dphi, weight);
41    }
42
43
44    void finalize() {
45      normalize(_h_deltaPhi.histos(), 1.);
46    }
47
48
49  private:
50
51    BinnedHistogram _h_deltaPhi;
52
53  };
54
55
56
57  RIVET_DECLARE_ALIASED_PLUGIN(CMS_2011_S8950903, CMS_2011_I885663);
58
59}