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CMS_2021_I1847230

Measurements of angular distance and momentum ratio distributions in three-jet and Z + two-jet final states in pp collisions at 8 and 13 TeV
Experiment: CMS (LHC)
Inspire ID: 1847230
Status: VALIDATED
Authors:
  • cms-pag-conveners-smp@cern.ch
  • Hannes Jung
  • Hyunyong Kim
  • Olga Kodolova
References:
  • arXiv: 2102.08816
  • CMS-SMP-17-008
  • EPJC (Submitted)
Beams: p+ p+
Beam energies: (4000.0, 4000.0); (6500.0, 6500.0) GeV
Run details:
  • QCD with pt>300 or Z -> mu+ mu-

Collinear (small-angle) and large-angle, as well as soft and hard radiations are investigated in three-jet and Z + two-jet events collected in proton-proton collisions at the LHC. The normalized production cross sections are measured as a function of the ratio of transverse momenta of two jets and their angular separation. The measurements in the three-jet and Z + two-jet events are based on data collected at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.8 fb^{-1}. The Z + two-jet events are reconstructed in the dimuon decay channel of the Z boson. The three-jet measurement is extended to include \sqrt{s} = 13 TeV data corresponding to an integrated luminosity of 2.3 fb^{-1}. The results are compared to predictions from event generators that include parton showers, multiple parton interactions, and hadronization. The collinear and soft regions are in general well described by parton showers, whereas the regions of large angular separation are often best described by calculations using higher-order matrix elements.

Source code: CMS_2021_I1847230.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/FastJets.hh"
  5#include "Rivet/Projections/ZFinder.hh"
  6
  7namespace Rivet {
  8
  9  /// @brief Measurements of angular distance and momentum ratio distributions in three-jet and Z + two-jet final states in pp collisions
 10  class CMS_2021_I1847230 : public Analysis {
 11  public:
 12
 13    CMS_2021_I1847230 ()
 14      : Analysis("CMS_2021_I1847230")
 15    {}
 16    void init() {
 17
 18      _mode = 0;
 19      if ( getOption("MODE") == "QCD8TeV" ) _mode = 1;
 20      else if ( getOption("MODE") == "QCD13TeV" ) _mode = 2;
 21      else if ( getOption("MODE") == "ZJet" ) _mode = 3;
 22      if (_mode == 1) {
 23         _jr = 0.5;
 24         book(_h1, "d01-x01-y01");
 25         book(_h2, "d02-x01-y01");
 26         book(_h3, "d03-x01-y01");
 27         book(_h4, "d04-x01-y01");
 28       }
 29       if (_mode == 2) {
 30         _jr = 0.4;
 31         book(_h1, "d05-x01-y01");
 32         book(_h2, "d06-x01-y01");
 33         book(_h3, "d07-x01-y01");
 34         book(_h4, "d08-x01-y01");
 35       }
 36       if (_mode == 1 or _mode == 2) {
 37         const FastJets jets(FinalState(), FastJets::ANTIKT, _jr);
 38         declare(jets, "jets");
 39       }
 40       if (_mode == 3) {
 41         FinalState fs(Cuts::abseta < 2.4 and Cuts::pT > 100*MeV);
 42         declare(fs, "FS");
 43  
 44         ZFinder zfinder(fs, Cuts::abseta < 5. and Cuts::pT > 30*GeV, PID::MUON, 70*GeV, 110*GeV,
 45              0.2, ZFinder::ChargedLeptons::PROMPT, ZFinder::ClusterPhotons::NODECAY, 
 46              ZFinder::AddPhotons::NO, 91.2*GeV);
 47  
 48         declare(zfinder, "ZFinder");
 49         declare(FastJets(zfinder.remainingFinalState(), FastJets::ANTIKT, 0.5), "JetsAK5_zj");
 50  
 51         book(_h1, "d09-x01-y01");  
 52         book(_h2, "d10-x01-y01");  
 53         book(_h3, "d11-x01-y01");  
 54         book(_h4, "d12-x01-y01"); 
 55 
 56         book(_ZJw_gen, "TMP/ZJw_gen");
 57       }
 58    }
 59
 60    void analyze(const Event& event) {
 61
 62      if (_mode == 1 or _mode ==2) {
 63        const Jets& jets = apply<JetAlg>(event, "jets").jetsByPt(Cuts::pT > 30.0*GeV);
 64        if (jets.size() < 3) vetoEvent;
 65        const FourMomentum jet1 = jets[0].momentum();
 66        const FourMomentum jet2 = jets[1].momentum();
 67        const FourMomentum jet3 = jets[2].momentum();
 68        
 69        if (jet1.pT() < 510.0*GeV) vetoEvent;
 70        if (jet1.absrapidity() > 2.5 or jet2.absrapidity() > 2.5) vetoEvent;
 71        const double del_phi12 = mapAngle0ToPi(jet2.phi() - jet1.phi());
 72        if (abs(del_phi12 - M_PI) > 1.0) vetoEvent;
 73        const double jet3_pt_jet2_pt = jet3.pT()/jet2.pT();
 74        if (!inRange(jet3_pt_jet2_pt, 0.1, 0.9)) vetoEvent;
 75        const double del_r23 = deltaR(jet3.rapidity(), jet3.phi(), jet2.rapidity(), jet2.phi());
 76        if (!inRange(del_r23, _jr+0.1, 1.5)) vetoEvent;
 77  
 78        if (del_r23 < 1.0) _h1->fill(jet3_pt_jet2_pt);
 79        if (del_r23 > 1.0) _h2->fill(jet3_pt_jet2_pt);
 80        if (jet3_pt_jet2_pt < 0.3) _h3->fill(del_r23);
 81        if (jet3_pt_jet2_pt > 0.6) _h4->fill(del_r23); 
 82      }
 83
 84      if (_mode == 3) { 
 85        const ZFinder& zfinder = apply<ZFinder>(event, "ZFinder");
 86        if (zfinder.bosons().size() != 1) vetoEvent;
 87        const Particle& z = zfinder.bosons()[0];
 88        const Particles leptons = sortBy(zfinder.constituents(), cmpMomByPt);
 89        if (leptons[0].pT() < 25.0*GeV or leptons[1].pT() < 10.0*GeV or z.pT() < 80.0*GeV) vetoEvent;
 90        if (leptons[0].absrapidity() > 2.1 or leptons[1].absrapidity() > 2.4) vetoEvent;
 91  
 92        const PseudoJets& psjetsAK5_zj = apply<FastJets>(event, "JetsAK5_zj").pseudoJetsByPt(20.0*GeV);
 93  
 94        if (psjetsAK5_zj.empty()) vetoEvent;
 95        
 96        const fastjet::PseudoJet& j0 = psjetsAK5_zj[0];
 97        const FourMomentum jmom0(j0.e(), j0.px(), j0.py(), j0.pz());
 98        
 99        if (jmom0.absrapidity() > 1.0 or jmom0.pT() < 80.0*GeV) vetoEvent;
100        if (!(deltaPhi(z, jmom0) > 2.0 and deltaR(leptons[0], jmom0) > 0.5 and deltaR(leptons[1], jmom0) > 0.5)) vetoEvent;
101        
102        _ZJw_gen ->fill(); 
103
104        if(psjetsAK5_zj.size() < 2) vetoEvent;
105        
106        const fastjet::PseudoJet& j1 = psjetsAK5_zj[1];
107        const FourMomentum jmom1(j1.e(), j1.px(), j1.py(), j1.pz());
108        if(deltaR(leptons[0], jmom1) < 0.5 or deltaR(leptons[1], jmom1) < 0.5 or jmom1.absrapidity() > 2.4) vetoEvent;
109        
110        const double dR_gen_Jj = deltaR(jmom0, jmom1);
111        if (!inRange(dR_gen_Jj, 0.5, 1.5)) vetoEvent;
112        const double rPt_gen_Jj = jmom1.pT()/jmom0.pT(); 
113         
114        if (dR_gen_Jj < 1.0) _h1->fill(rPt_gen_Jj);
115        if (dR_gen_Jj > 1.0) _h2->fill(rPt_gen_Jj);
116        if (rPt_gen_Jj < 0.3) _h3->fill(dR_gen_Jj);
117        if (rPt_gen_Jj > 0.6) _h4->fill(dR_gen_Jj);
118      }
119    }
120
121    void finalize() {
122      if (_mode == 1 or _mode == 2) {
123        normalize(_h1);
124        normalize(_h2);
125        normalize(_h3);
126        normalize(_h4);
127        //scale(_h1, 1.0/_h1->effNumEntries());
128        //scale(_h2, 1.0/_h2->effNumEntries());
129        //scale(_h3, 1.0/_h3->effNumEntries());
130        //scale(_h4, 1.0/_h4->effNumEntries());
131      }
132      if (_mode == 3) {
133        for (size_t i = 0; i < _h1->numBins(); i++) {
134          _h1->bin(i).scaleW(_h1->bin(i).width());
135        }
136        for (size_t i = 0; i < _h2->numBins(); i++) {
137          _h2->bin(i).scaleW(_h2->bin(i).width());
138        }
139        for (size_t i = 0; i < _h3->numBins(); i++) {
140          _h3->bin(i).scaleW(_h3->bin(i).width());
141        }
142        for (size_t i = 0; i < _h4->numBins(); i++) {
143          _h4->bin(i).scaleW(_h4->bin(i).width());
144        }
145        scale(_h1, 1.0/ *_ZJw_gen);
146        scale(_h2, 1.0/ *_ZJw_gen);
147        scale(_h3, 1.0/ *_ZJw_gen);
148        scale(_h4, 1.0/ *_ZJw_gen);
149      }
150    }
151
152  private:
153
154    Histo1DPtr  _h1;
155    Histo1DPtr  _h2;
156    Histo1DPtr  _h3;
157    Histo1DPtr  _h4;
158    
159    CounterPtr _ZJw_gen;
160
161    double _jr; 
162
163  protected:
164
165    size_t _mode;
166
167  };
168
169  DECLARE_RIVET_PLUGIN(CMS_2021_I1847230);
170}