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Rivet analyses reference

ATLAS_2012_I943401

Search for supersymmetry with 2 leptons and missing transverse energy
Experiment: ATLAS (LHC)
Inspire ID: 943401
Status: VALIDATED
Authors:
  • Peter Richardson
References: Beams: p+ p+
Beam energies: (3500.0, 3500.0) GeV
Run details:
  • BSM signal events at 7000 GeV.

Results of three searches for the production of supersymmetric particles decaying into final states with missing transverse momentum and exactly two isolated leptons, electrons or muons. The analysis uses a data sample collected during the first half of 2011 that corresponds to a total integrated luminosity of 1 $\text{fb}^{-1}$ of $\sqrt{s} = 7$\,TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. Opposite-sign and same-sign dilepton events are studied separately. Additionally, in opposite- sign events, a search is made for an excess of same-flavour over different-flavour lepton pairs.

Source code: ATLAS_2012_I943401.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Tools/BinnedHistogram.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/VisibleFinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/VetoedFinalState.hh"

namespace Rivet {


  class ATLAS_2012_I943401 : public Analysis {
  public:

    /// @name Constructors etc.
    //@{

    /// Constructor

    ATLAS_2012_I943401()
      : Analysis("ATLAS_2012_I943401")
    {    }

    //@}


  public:

    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {

      // projection to find the electrons
      IdentifiedFinalState elecs(Cuts::abseta < 2.47 && Cuts::pT > 20*GeV);
      elecs.acceptIdPair(PID::ELECTRON);
      declare(elecs, "elecs");

      // projection to find the muons
      IdentifiedFinalState muons(Cuts::abseta < 2.4 && Cuts::pT > 10*GeV);
      muons.acceptIdPair(PID::MUON);
      declare(muons, "muons");

      // jet finder
      VetoedFinalState vfs;
      vfs.addVetoPairId(PID::MUON);
      declare(FastJets(vfs, FastJets::ANTIKT, 0.4), "AntiKtJets04");

      // all tracks (to do deltaR with leptons)
      declare(ChargedFinalState(Cuts::abseta < 3 && Cuts::pT > 0.5*GeV), "cfs");

      // for pTmiss
      declare(VisibleFinalState(Cuts::abseta < 4.5), "vfs");

      // book histograms

      // counts in signal regions
      _count_OS_SR1 = bookHisto1D("count_OS_SR1", 1, 0., 1.);
      _count_OS_SR2 = bookHisto1D("count_OS_SR2", 1, 0., 1.);
      _count_OS_SR3 = bookHisto1D("count_OS_SR3", 1, 0., 1.);
      _count_SS_SR1 = bookHisto1D("count_SS_SR1", 1, 0., 1.);
      _count_SS_SR2 = bookHisto1D("count_SS_SR2", 1, 0., 1.);
      _count_FS_SR1 = bookHisto1D("count_FS_SR1", 1, 0., 1.);
      _count_FS_SR2 = bookHisto1D("count_FS_SR2", 1, 0., 1.);
      _count_FS_SR3 = bookHisto1D("count_FS_SR3", 1, 0., 1.);

      // histograms from paper

      _hist_mll_SS_D         = bookHisto1D( 1,1,1);
      _hist_mll_SS_B         = bookHisto1D( 1,1,2);
      _hist_eTmiss_SS_D      = bookHisto1D( 2,1,1);
      _hist_eTmiss_SS_B      = bookHisto1D( 2,1,2);
      _hist_mll_SS_2Jet_D    = bookHisto1D( 3,1,1);
      _hist_mll_SS_2Jet_B    = bookHisto1D( 3,1,2);
      _hist_njet_SS_D        = bookHisto1D( 5,1,1);
      _hist_njet_SS_B        = bookHisto1D( 5,1,2);
      _hist_pT_j1_SS_D       = bookHisto1D( 6,1,1);
      _hist_pT_j1_SS_B       = bookHisto1D( 6,1,2);
      _hist_pT_j2_SS_D       = bookHisto1D( 7,1,1);
      _hist_pT_j2_SS_B       = bookHisto1D( 7,1,2);
      _hist_pT_l1_SS_D       = bookHisto1D( 8,1,1);
      _hist_pT_l1_SS_B       = bookHisto1D( 8,1,2);
      _hist_pT_l2_SS_D       = bookHisto1D( 9,1,1);
      _hist_pT_l2_SS_B       = bookHisto1D( 9,1,2);
      _hist_mll_OS_D         = bookHisto1D(10,1,1);
      _hist_mll_OS_B         = bookHisto1D(10,1,2);
      _hist_eTmiss_OS_D      = bookHisto1D(11,1,1);
      _hist_eTmiss_OS_B      = bookHisto1D(11,1,2);
      _hist_eTmiss_3Jet_OS_D = bookHisto1D(12,1,1);
      _hist_eTmiss_3Jet_OS_B = bookHisto1D(12,1,2);
      _hist_eTmiss_4Jet_OS_D = bookHisto1D(13,1,1);
      _hist_eTmiss_4Jet_OS_B = bookHisto1D(13,1,2);
      _hist_njet_OS_D        = bookHisto1D(14,1,1);
      _hist_njet_OS_B        = bookHisto1D(14,1,2);
      _hist_pT_j1_OS_D       = bookHisto1D(15,1,1);
      _hist_pT_j1_OS_B       = bookHisto1D(15,1,2);
      _hist_pT_j2_OS_D       = bookHisto1D(16,1,1);
      _hist_pT_j2_OS_B       = bookHisto1D(16,1,2);
      _hist_pT_l1_OS_D       = bookHisto1D(17,1,1);
      _hist_pT_l1_OS_B       = bookHisto1D(17,1,2);
      _hist_pT_l2_OS_D       = bookHisto1D(18,1,1);
      _hist_pT_l2_OS_B       = bookHisto1D(18,1,2);
      //????
      //   <dataPointSet name="d04-x01-y01" dimension="2" path="/REF/ATLAS_2011_I943401" title="EVENTS/10 GEV" >
      //   <dataPointSet name="d04-x01-y02" dimension="2" path="/REF/ATLAS_2011_I943401" title="EVENTS/10 GEV" >
    }

    /// Perform the event analysis
    void analyze(const Event& event) {
      // event weight
      const double weight = event.weight();

      // get the jet candidates
      Jets cand_jets;
      foreach (const Jet& jet,
        apply<FastJets>(event, "AntiKtJets04").jetsByPt(20.0*GeV) ) {
        if ( fabs( jet.eta() ) < 2.8 ) {
          cand_jets.push_back(jet);
        }
      }

      // electron candidates
      Particles cand_e =
        apply<IdentifiedFinalState>(event, "elecs").particlesByPt();

      // Discard jets that overlap with electrons
      Jets recon_jets;
      foreach ( const Jet& jet, cand_jets ) {
        bool away_from_e = true;
          foreach ( const Particle& e, cand_e ) {
            if ( deltaR(e.momentum(),jet.momentum()) <= 0.2 ) {
              away_from_e = false;
              break;
            }
          }
          if ( away_from_e ) recon_jets.push_back( jet );
      }
      // get the charged tracks for isolation
      Particles chg_tracks =
        apply<ChargedFinalState>(event, "cfs").particles();

      // Reconstructed electrons
      Particles recon_e;
      foreach ( const Particle& e, cand_e ) {
        // check not near a jet
        bool e_near_jet = false;
        foreach ( const Jet& jet, recon_jets ) {
          if ( deltaR(e.momentum(),jet.momentum()) < 0.4 ) {
            e_near_jet = true;
            break;
          }
        }
        if ( e_near_jet ) continue;
        // check the isolation
        double pTinCone = -e.pT();
        foreach ( const Particle& track, chg_tracks ) {
          if ( deltaR(e.momentum(),track.momentum()) < 0.2 )
            pTinCone += track.pT();
        }
        if ( pTinCone < 0.1*e.perp() )
          recon_e.push_back(e);
      }

      // Reconstructed Muons
      Particles recon_mu;
      Particles cand_mu =
        apply<IdentifiedFinalState>(event,"muons").particlesByPt();
      foreach ( const Particle& mu, cand_mu ) {
        // check not near a jet
        bool mu_near_jet = false;
        foreach ( const Jet& jet, recon_jets ) {
          if ( deltaR(mu.momentum(),jet.momentum()) < 0.4 ) {
            mu_near_jet = true;
            break;
          }
        }
        if ( mu_near_jet ) continue;
        // isolation
        double pTinCone = -mu.pT();
        foreach ( const Particle& track, chg_tracks ) {
          if ( deltaR(mu.momentum(),track.momentum()) < 0.2 )
            pTinCone += track.pT();
        }
        if ( pTinCone < 1.8*GeV )
          recon_mu.push_back(mu);
      }

      // pTmiss
      Particles vfs_particles
        = apply<VisibleFinalState>(event, "vfs").particles();
      FourMomentum pTmiss;
      foreach ( const Particle& p, vfs_particles ) {
        pTmiss -= p.momentum();
      }
      double eTmiss = pTmiss.pT();

      // ATLAS calo problem
      if(rand()/static_cast<double>(RAND_MAX)<=0.42) {
        foreach ( const Particle& e, recon_e ) {
          double eta = e.eta();
          double phi = e.azimuthalAngle(MINUSPI_PLUSPI);
          if (inRange(eta, -0.1, 1.5) && inRange(phi, -0.9, -0.5)) vetoEvent;
        }
        foreach ( const Jet& jet, recon_jets ) {
          double eta = jet.rapidity();
          double phi = jet.azimuthalAngle(MINUSPI_PLUSPI);
          if (jet.pT() > 40*GeV && inRange(eta, -0.1, 1.5) && inRange(phi, -0.9, -0.5)) vetoEvent;
        }
      }

      // Exactly two leptons for each event
      if ( recon_mu.size() + recon_e.size() != 2) vetoEvent;
      // two electrons highest pT > 25
      Particles recon_leptons;
      if (recon_e.size()==2 && recon_e[0].pT()>25*GeV) {
        recon_leptons = recon_e;
      }
      // two muons highest pT > 20
      else if (recon_mu.size()==2 && recon_mu[0].pT() > 20*GeV) {
        recon_leptons = recon_mu;
      } else if (recon_e.size()==1 && recon_mu.size()==1 &&
                 (recon_e[0].pT() > 25*GeV || recon_mu[0].pT() > 20*GeV )) {
        if (recon_mu[0].pT() < recon_e[0].pT()) {
          recon_leptons.push_back(recon_e [0]);
          recon_leptons.push_back(recon_mu[0]);
        } else {
          recon_leptons.push_back(recon_mu[0]);
          recon_leptons.push_back(recon_e [0]);
        }
      }
      // fails trigger
      else vetoEvent;

      double mll = (recon_leptons[0].momentum()+recon_leptons[1].momentum()).mass();
      // lepton pair mass > 12.
      if (mll < 12*GeV) vetoEvent;

      // same sign or opposite sign event
      int sign = recon_leptons[0].pid()*recon_leptons[1].pid();

      // same sign leptons
      if(sign>0) {
        _hist_mll_SS_D   ->fill(mll   ,weight);
        _hist_mll_SS_B   ->fill(mll   ,weight);
        _hist_eTmiss_SS_D->fill(eTmiss,weight);
        _hist_eTmiss_SS_B->fill(eTmiss,weight);
        if(recon_jets.size()>=2) {
          _hist_mll_SS_2Jet_D   ->fill(mll   ,weight);
          _hist_mll_SS_2Jet_B   ->fill(mll   ,weight);
        }
        _hist_njet_SS_D ->fill(recon_jets.size(),weight);
        _hist_njet_SS_B ->fill(recon_jets.size(),weight);
        if(!recon_jets.empty()) {
          _hist_pT_j1_SS_D->fill(recon_jets[0].perp(),weight);
          _hist_pT_j1_SS_B->fill(recon_jets[0].perp(),weight);
        }
        if(recon_jets.size()>2) {
          _hist_pT_j2_SS_D->fill(recon_jets[1].perp(),weight);
          _hist_pT_j2_SS_B->fill(recon_jets[1].perp(),weight);
        }
        _hist_pT_l1_SS_D->fill(recon_leptons[0].perp(),weight);
        _hist_pT_l1_SS_B->fill(recon_leptons[0].perp(),weight);
        _hist_pT_l2_SS_D->fill(recon_leptons[1].perp(),weight);
        _hist_pT_l2_SS_B->fill(recon_leptons[1].perp(),weight);
        // SS-SR1
        if(eTmiss>100.) {
          _count_SS_SR1->fill(0.5,weight);
        }
        // SS-SR2
        if(eTmiss>80. && recon_jets.size()>=2 &&
           recon_jets[1].perp()>50.) {
          _count_SS_SR2->fill(0.5,weight);
        }
      }
      // opposite sign
      else {
        _hist_mll_OS_D->fill(mll   ,weight);
        _hist_mll_OS_B->fill(mll   ,weight);
        _hist_eTmiss_OS_D->fill(eTmiss,weight);
        _hist_eTmiss_OS_B->fill(eTmiss,weight);
        if(recon_jets.size()>=3){
          _hist_eTmiss_3Jet_OS_D->fill(eTmiss,weight);
          _hist_eTmiss_3Jet_OS_B->fill(eTmiss,weight);
        }
        if(recon_jets.size()>=4){
          _hist_eTmiss_4Jet_OS_D->fill(eTmiss,weight);
          _hist_eTmiss_4Jet_OS_B->fill(eTmiss,weight);
        }
        _hist_njet_OS_D->fill(recon_jets.size(),weight);
        _hist_njet_OS_B->fill(recon_jets.size(),weight);
        if(!recon_jets.empty()) {
          _hist_pT_j1_OS_D->fill(recon_jets[0].perp(),weight);
          _hist_pT_j1_OS_B->fill(recon_jets[0].perp(),weight);
        }
        if(recon_jets.size()>2) {
          _hist_pT_j2_OS_D->fill(recon_jets[1].perp(),weight);
          _hist_pT_j2_OS_B->fill(recon_jets[1].perp(),weight);
        }
        _hist_pT_l1_OS_D->fill(recon_leptons[0].perp(),weight);
        _hist_pT_l1_OS_B->fill(recon_leptons[0].perp(),weight);
        _hist_pT_l2_OS_D->fill(recon_leptons[1].perp(),weight);
        _hist_pT_l2_OS_B->fill(recon_leptons[1].perp(),weight);
        // different signal regions
        // OS-SR1
        if(eTmiss>250.) {
          _count_OS_SR1->fill(0.5,weight);
        }
        // OS-SR2
        if(eTmiss>220. && recon_jets.size()>=3 &&
           recon_jets[0].perp()>80. &&
           recon_jets[2].perp()>40.) {
          _count_OS_SR2->fill(0.5,weight);
        }
        // OS-SR3
        if(eTmiss>100. && recon_jets.size()>=4 &&
           recon_jets[0].perp()>100. &&
           recon_jets[3].perp()>70.) {
          _count_OS_SR3->fill(0.5,weight);
        }
        // same flavour analysis
        static const double beta   = 0.75;
        static const double tau_e  = 0.96;
        static const double tau_mu = 0.816;
        double fs_weight = weight;
        if (recon_leptons[0].abspid() == PID::ELECTRON && recon_leptons[1].abspid() == PID::ELECTRON) {
          fs_weight /= beta*(1.-sqr(1.-tau_e));
        } else if (recon_leptons[0].abspid() == PID::MUON && recon_leptons[1].abspid()==PID::MUON) {
          fs_weight *= beta/(1.-sqr(1.-tau_mu));
        } else {
          fs_weight /= -(1.-(1.-tau_e)*(1.-tau_mu));
        }
        // FS-SR1
        if(eTmiss>80.&& (mll<80.||mll>100.)) {
          _count_FS_SR1->fill(0.5,fs_weight);
        }
        // FS-SR2
        if(eTmiss>80.&&recon_jets.size()>=2) {
          _count_FS_SR2->fill(0.5,fs_weight);
        }
        // FS-SR3
        if(eTmiss>250.) {
          _count_FS_SR3->fill(0.5,fs_weight);
        }
      }
    }

    //@}


    void finalize() {

      double norm = crossSection()/femtobarn*1.04/sumOfWeights();
      // event counts
      scale(_count_OS_SR1,norm);
      scale(_count_OS_SR2,norm);
      scale(_count_OS_SR3,norm);
      scale(_count_SS_SR1,norm);
      scale(_count_SS_SR2,norm);
      scale(_count_FS_SR1,norm);
      scale(_count_FS_SR2,norm);
      scale(_count_FS_SR3,norm);
      // histograms
      scale(_hist_mll_SS_D     ,norm*20.);
      scale(_hist_mll_SS_B     ,norm*20.);
      scale(_hist_eTmiss_SS_D  ,norm*20.);
      scale(_hist_eTmiss_SS_B  ,norm*20.);
      scale(_hist_mll_SS_2Jet_D,norm*50.);
      scale(_hist_mll_SS_2Jet_B,norm*50.);
      scale(_hist_njet_SS_D    ,norm    );
      scale(_hist_njet_SS_B    ,norm    );
      scale(_hist_pT_j1_SS_D   ,norm*20.);
      scale(_hist_pT_j1_SS_B   ,norm*20.);
      scale(_hist_pT_j2_SS_D   ,norm*20.);
      scale(_hist_pT_j2_SS_B   ,norm*20.);
      scale(_hist_pT_l1_SS_D   ,norm*5. );
      scale(_hist_pT_l1_SS_B   ,norm*5. );
      scale(_hist_pT_l2_SS_D   ,norm*5. );
      scale(_hist_pT_l2_SS_B   ,norm*5. );

      scale(_hist_mll_OS_D        ,norm*10.);
      scale(_hist_mll_OS_B        ,norm*10.);
      scale(_hist_eTmiss_OS_D     ,norm*10.);
      scale(_hist_eTmiss_OS_B     ,norm*10.);
      scale(_hist_eTmiss_3Jet_OS_D,norm*10.);
      scale(_hist_eTmiss_3Jet_OS_B,norm*10.);
      scale(_hist_eTmiss_4Jet_OS_D,norm*10.);
      scale(_hist_eTmiss_4Jet_OS_B,norm*10.);
      scale(_hist_njet_OS_D       ,norm    );
      scale(_hist_njet_OS_B       ,norm    );
      scale(_hist_pT_j1_OS_D      ,norm*20.);
      scale(_hist_pT_j1_OS_B      ,norm*20.);
      scale(_hist_pT_j2_OS_D      ,norm*20.);
      scale(_hist_pT_j2_OS_B      ,norm*20.);
      scale(_hist_pT_l1_OS_D      ,norm*20.);
      scale(_hist_pT_l1_OS_B      ,norm*20.);
      scale(_hist_pT_l2_OS_D      ,norm*20.);
      scale(_hist_pT_l2_OS_B      ,norm*20.);
    }

  private:

    /// @name Histograms
    //@{
    Histo1DPtr _count_OS_SR1;
    Histo1DPtr _count_OS_SR2;
    Histo1DPtr _count_OS_SR3;
    Histo1DPtr _count_SS_SR1;
    Histo1DPtr _count_SS_SR2;
    Histo1DPtr _count_FS_SR1;
    Histo1DPtr _count_FS_SR2;
    Histo1DPtr _count_FS_SR3;

    Histo1DPtr _hist_mll_SS_D;
    Histo1DPtr _hist_mll_SS_B;
    Histo1DPtr _hist_eTmiss_SS_D;
    Histo1DPtr _hist_eTmiss_SS_B;
    Histo1DPtr _hist_mll_SS_2Jet_D;
    Histo1DPtr _hist_mll_SS_2Jet_B;
    Histo1DPtr _hist_njet_SS_D;
    Histo1DPtr _hist_njet_SS_B;
    Histo1DPtr _hist_pT_j1_SS_D;
    Histo1DPtr _hist_pT_j1_SS_B;
    Histo1DPtr _hist_pT_j2_SS_D;
    Histo1DPtr _hist_pT_j2_SS_B;
    Histo1DPtr _hist_pT_l1_SS_D;
    Histo1DPtr _hist_pT_l1_SS_B;
    Histo1DPtr _hist_pT_l2_SS_D;
    Histo1DPtr _hist_pT_l2_SS_B;

    Histo1DPtr _hist_mll_OS_D;
    Histo1DPtr _hist_mll_OS_B;
    Histo1DPtr _hist_eTmiss_OS_D;
    Histo1DPtr _hist_eTmiss_OS_B;
    Histo1DPtr _hist_eTmiss_3Jet_OS_D;
    Histo1DPtr _hist_eTmiss_3Jet_OS_B;
    Histo1DPtr _hist_eTmiss_4Jet_OS_D;
    Histo1DPtr _hist_eTmiss_4Jet_OS_B;
    Histo1DPtr _hist_njet_OS_D ;
    Histo1DPtr _hist_njet_OS_B ;
    Histo1DPtr _hist_pT_j1_OS_D;
    Histo1DPtr _hist_pT_j1_OS_B;
    Histo1DPtr _hist_pT_j2_OS_D;
    Histo1DPtr _hist_pT_j2_OS_B;
    Histo1DPtr _hist_pT_l1_OS_D;
    Histo1DPtr _hist_pT_l1_OS_B;
    Histo1DPtr _hist_pT_l2_OS_D;
    Histo1DPtr _hist_pT_l2_OS_B;
    //@}
  };

  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(ATLAS_2012_I943401);

}