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Rivet analyses reference

CMS_2018_I1643640

Azimuthal correlations for inclusive 2-jet, 3-jet, and 4-jet events in pp collisions at $\sqrt{s}$ = 13 TeV
Experiment: CMS (LHC)
Inspire ID: 1643640
Status: VALIDATED
Authors:
  • cms-pag-conveners-smp@cern.ch
  • Hannes Jung
  • Paolo Gunnellini
  • Panos Kokkas
References:
  • 10.1140/epjc/s10052-018-6033-4
  • arxiv:1712.05471
  • CMS-SMP-16-014
Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
  • QCD at $\sqrt{s} = 13\;\text{TeV}$

Azimuthal correlations between the two jets with the largest transverse momenta $p_T$ in inclusive 2-, 3-, and 4-jet events are presented for several regions of the leading jet $p_T$ up to 4 TeV. For 3- and 4-jet scenarios, measurements of the minimum azimuthal angles between any two of the three or four leading $p_T$ jets are also presented. The analysis is based on data from proton-proton collisions collected by the CMS Collaboration at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Calculations based on leading-order matrix elements supplemented with parton showering and hadronization do not fully describe the data, so next-to-leading-order calculations matched with parton shower and hadronization models are needed to better describe the measured distributions. Furthermore, we show that azimuthal jet correlations are sensitive to details of the parton showering, hadronization, and multiparton interactions. A next-to-leading-order calculation matched with parton showers in the MC\@NLO method, as implemented in HERWIG 7, gives a better overall description of the measurements than the POWHEG method.

Source code: CMS_2018_I1643640.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Tools/BinnedHistogram.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/FastJets.hh"

namespace Rivet {


  /// CMS Azimuthal corellations at 13 TeV
  class CMS_2018_I1643640 : public Analysis {
  public:

    DEFAULT_RIVET_ANALYSIS_CTOR(CMS_2018_I1643640);

    void init() {
      FinalState fs;
      FastJets akt(fs, FastJets::ANTIKT, 0.4);
      declare(akt, "antikT");

      Histo1DPtr tmp;

      _h_deltaPhi_2J_phi12.add( 200.,  300., book(tmp, 1, 1, 1));
      _h_deltaPhi_2J_phi12.add( 300.,  400., book(tmp, 2, 1, 1));
      _h_deltaPhi_2J_phi12.add( 400.,  500., book(tmp, 3, 1, 1));
      _h_deltaPhi_2J_phi12.add( 500.,  600., book(tmp, 4, 1, 1));
      _h_deltaPhi_2J_phi12.add( 600.,  700., book(tmp, 5, 1, 1));
      _h_deltaPhi_2J_phi12.add( 700.,  800., book(tmp, 6, 1, 1));
      _h_deltaPhi_2J_phi12.add( 800.,  1000., book(tmp, 7, 1, 1));
      _h_deltaPhi_2J_phi12.add( 1000., 1200., book(tmp, 8, 1, 1));
      _h_deltaPhi_2J_phi12.add( 1200., 7000., book(tmp, 9, 1, 1));

      _h_deltaPhi_3J_phi12.add( 200.,  300., book(tmp, 10, 1, 1));
      _h_deltaPhi_3J_phi12.add( 300.,  400., book(tmp, 11, 1, 1));
      _h_deltaPhi_3J_phi12.add( 400.,  500., book(tmp, 12, 1, 1));
      _h_deltaPhi_3J_phi12.add( 500.,  600., book(tmp, 13, 1, 1));
      _h_deltaPhi_3J_phi12.add( 600.,  700., book(tmp, 14, 1, 1));
      _h_deltaPhi_3J_phi12.add( 700.,  800., book(tmp, 15, 1, 1));
      _h_deltaPhi_3J_phi12.add( 800.,  1000., book(tmp, 16, 1, 1));
      _h_deltaPhi_3J_phi12.add( 1000., 7000., book(tmp, 17, 1, 1));

      _h_deltaPhi_4J_phi12.add( 200.,  300., book(tmp, 18, 1, 1));
      _h_deltaPhi_4J_phi12.add( 300.,  400., book(tmp, 19, 1, 1));
      _h_deltaPhi_4J_phi12.add( 400.,  500., book(tmp, 20, 1, 1));
      _h_deltaPhi_4J_phi12.add( 500.,  600., book(tmp, 21, 1, 1));
      _h_deltaPhi_4J_phi12.add( 600.,  700., book(tmp, 22, 1, 1));
      _h_deltaPhi_4J_phi12.add( 700.,  800., book(tmp, 23, 1, 1));
      _h_deltaPhi_4J_phi12.add( 800.,  1000., book(tmp, 24, 1, 1));
      _h_deltaPhi_4J_phi12.add( 1000., 7000., book(tmp, 25, 1, 1));

      _h_deltaPhi_3J_phimin2J.add( 200.,  300., book(tmp, 26, 1, 1));
      _h_deltaPhi_3J_phimin2J.add( 300.,  400., book(tmp, 27, 1, 1));
      _h_deltaPhi_3J_phimin2J.add( 400.,  500., book(tmp, 28, 1, 1));
      _h_deltaPhi_3J_phimin2J.add( 500.,  600., book(tmp, 29, 1, 1));
      _h_deltaPhi_3J_phimin2J.add( 600.,  700., book(tmp, 30, 1, 1));
      _h_deltaPhi_3J_phimin2J.add( 700.,  800., book(tmp, 31, 1, 1));
      _h_deltaPhi_3J_phimin2J.add( 800.,  1000., book(tmp, 32, 1, 1));
      _h_deltaPhi_3J_phimin2J.add( 1000., 7000., book(tmp, 33, 1, 1));

      _h_deltaPhi_4J_phimin2J.add( 200.,  300., book(tmp, 34, 1, 1));
      _h_deltaPhi_4J_phimin2J.add( 300.,  400., book(tmp, 35, 1, 1));
      _h_deltaPhi_4J_phimin2J.add( 400.,  500., book(tmp, 36, 1, 1));
      _h_deltaPhi_4J_phimin2J.add( 500.,  600., book(tmp, 37, 1, 1));
      _h_deltaPhi_4J_phimin2J.add( 600.,  700., book(tmp, 38, 1, 1));
      _h_deltaPhi_4J_phimin2J.add( 700.,  800., book(tmp, 39, 1, 1));
      _h_deltaPhi_4J_phimin2J.add( 800.,  1000., book(tmp, 40, 1, 1));
      _h_deltaPhi_4J_phimin2J.add( 1000., 7000., book(tmp, 41, 1, 1));

    }


    void analyze(const Event & event) {
      const Jets& jets = apply<JetAlg>(event, "antikT").jetsByPt();

      // 2 jet case and Delta_phi12
      if( jets.size() >= 2 ) {
        if ( (jets[0].pT() >= 200.*GeV)  &&  (jets[1].pT() >= 100.*GeV) ) {
          if ( (fabs(jets[0].rap()) <= 2.5)  &&  (fabs(jets[1].rap()) <= 2.5) ) {
            double dphi = deltaPhi(jets[0].phi(), jets[1].phi());
            _h_deltaPhi_2J_phi12.fill(jets[0].pT(), dphi, 1.0);
          }
        }
      }

      // 3 jet case and Delta_phi12
      if ( jets.size() >= 3 ) {
        if ( (jets[0].pT() >= 200.*GeV)  &&  (jets[1].pT() >= 100.*GeV)  && (jets[2].pT() >= 100.*GeV) ) {
          if ( (fabs(jets[0].rap()) <= 2.5)  &&  (fabs(jets[1].rap()) <= 2.5) &&  (fabs(jets[2].rap()) <= 2.5)) {
            double dphi = deltaPhi(jets[0].phi(), jets[1].phi());
            _h_deltaPhi_3J_phi12.fill(jets[0].pT(), dphi, 1.0);
          }
        }
      }

      // 4 jet case and Delta_phi12
      if ( jets.size() >= 4 ) {
        if ( (jets[0].pT() >= 200.*GeV)  &&  (jets[1].pT() >= 100.*GeV)  && (jets[2].pT() >= 100.*GeV)   && (jets[3].pT() >= 100.*GeV)) {
          if ( (fabs(jets[0].rap()) <= 2.5)  &&  (fabs(jets[1].rap()) <= 2.5) &&  (fabs(jets[2].rap()) <= 2.5) &&  (fabs(jets[3].rap()) <= 2.5)) {
            double dphi = deltaPhi(jets[0].phi(), jets[1].phi());
            _h_deltaPhi_4J_phi12.fill(jets[0].pT(), dphi, 1.0);
          }
        }
      }

      // 3 jet case and Delta_Phi_min2j
      if ( jets.size() >= 3 ) {
        if ( (jets[0].pT() >= 200.*GeV)  &&  (jets[1].pT() >= 100.*GeV)  && (jets[2].pT() >= 100.*GeV) ) {
          if ( (fabs(jets[0].rap()) <= 2.5)  &&  (fabs(jets[1].rap()) <= 2.5) &&  (fabs(jets[2].rap()) <= 2.5)) {
            double dphi01 = deltaPhi(jets[0].phi(), jets[1].phi());
            if (dphi01 >= PI/2. ){
              double dphi02 = deltaPhi(jets[0].phi(), jets[2].phi());
              double dphi12 = deltaPhi(jets[1].phi(), jets[2].phi());
              // evaluate DPhi2Jmin
              vector<double> Dphis2J{dphi01,dphi02,dphi12};
              double DPhi2Jmin = min(Dphis2J);
              // double Dphis2J[3] = {dphi01,dphi02,dphi12};
              // double DPhi2Jmin = Dphis2J[0];
              // for (int gg=1; gg<3; ++gg) { if (DPhi2Jmin>Dphis2J[gg]) DPhi2Jmin = Dphis2J[gg]; }
              _h_deltaPhi_3J_phimin2J.fill(jets[0].pT(), DPhi2Jmin, 1.0);
            }
          }
        }
      }

      // 4 jet case and Delta_Phi_min2j
      if ( jets.size() >= 4 ) {
        if ( (jets[0].pT() >= 200.*GeV)  &&  (jets[1].pT() >= 100.*GeV)  && (jets[2].pT() >= 100.*GeV)   && (jets[3].pT() >= 100.*GeV)) {
          if ( (fabs(jets[0].rap()) <= 2.5)  &&  (fabs(jets[1].rap()) <= 2.5) &&  (fabs(jets[2].rap()) <= 2.5) &&  (fabs(jets[3].rap()) <= 2.5)) {
            double dphi01 = deltaPhi(jets[0].phi(), jets[1].phi());
            if (dphi01 >= PI/2.) {
              double dphi02 = deltaPhi(jets[0].phi(), jets[2].phi());
              double dphi03 = deltaPhi(jets[0].phi(), jets[3].phi());
              double dphi12 = deltaPhi(jets[1].phi(), jets[2].phi());
              double dphi13 = deltaPhi(jets[1].phi(), jets[3].phi());
              double dphi23 = deltaPhi(jets[2].phi(), jets[3].phi());
              /// evaluate DPhi2Jmin
              // double Dphis2J[6]={dphi01,dphi02,dphi03,dphi12,dphi13,dphi23};
              // double DPhi2Jmin=Dphis2J[0];
              // for(int gg=1; gg<6; ++gg){ if(DPhi2Jmin>Dphis2J[gg]){DPhi2Jmin=Dphis2J[gg];} }
              vector<double> Dphis2J{dphi01,dphi02,dphi03,dphi12,dphi13,dphi23};
              double DPhi2Jmin = min(Dphis2J);
              _h_deltaPhi_4J_phimin2J.fill(jets[0].pT(), DPhi2Jmin, 1.0);
            }
          }
        }
      }
    }  // end analyze


    void finalize() {
      for (Histo1DPtr histo : _h_deltaPhi_2J_phi12.histos()) normalize(histo);
      for (Histo1DPtr histo : _h_deltaPhi_3J_phi12.histos()) normalize(histo);
      for (Histo1DPtr histo : _h_deltaPhi_4J_phi12.histos()) normalize(histo);
      for (Histo1DPtr histo : _h_deltaPhi_3J_phimin2J.histos()) normalize(histo);
      for (Histo1DPtr histo : _h_deltaPhi_4J_phimin2J.histos()) normalize(histo);
    }


  private:

    BinnedHistogram _h_deltaPhi_2J_phi12;
    BinnedHistogram _h_deltaPhi_3J_phi12;
    BinnedHistogram _h_deltaPhi_4J_phi12;
    BinnedHistogram _h_deltaPhi_3J_phimin2J;
    BinnedHistogram _h_deltaPhi_4J_phimin2J;

  };


  DECLARE_RIVET_PLUGIN(CMS_2018_I1643640);

}