Rivet analyses

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/VisibleFinalState.hh"

namespace Rivet {


  class ATLAS_2011_I890749 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2011_I890749);


    /// @name Analysis methods
    /// @{

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

      // projection to find the electrons
      Cut pt10 = Cuts::pT > 10.0 * GeV;
      IdentifiedFinalState elecs(Cuts::abseta < 2.47 && pt10);
      elecs.acceptIdPair(PID::ELECTRON);
      declare(elecs, "elecs");

      // veto region electrons
      Cut vetocut = Cuts::absetaIn(1.37, 1.52);
      IdentifiedFinalState veto_elecs(vetocut && pt10);
      veto_elecs.acceptIdPair(PID::ELECTRON);
      declare(veto_elecs, "veto_elecs");

      // projection to find the muons
      IdentifiedFinalState muons(Cuts::abseta < 2.4 && pt10);
      muons.acceptIdPair(PID::MUON);
      declare(muons, "muons");

      VetoedFinalState vfs;
      vfs.addVetoPairId(PID::MUON);

      /// Jet finder
      declare(FastJets(vfs, JetAlg::ANTIKT, 0.4), "AntiKtJets04");

      // all tracks (to do deltaR with leptons)
      declare(ChargedFinalState(Cuts::abseta < 3.0), "cfs");

      // for pTmiss
      declare(VisibleFinalState(Cuts::abseta < 4.9), "vfs");

      /// Book histograms
      book(_count_A, "count_A", 1, 0., 1.);
      book(_count_B, "count_B", 1, 0., 1.);
      book(_count_C, "count_C", 1, 0., 1.);
      book(_count_D, "count_D", 1, 0., 1.);

      book(_hist_meff_A, "m_eff_A", 30, 0., 3000.);
      book(_hist_mT2_B, "m_T2", 25, 0., 1000.);
      book(_hist_meff_CD, "m_eff_C_D", 30, 0., 3000.);
      book(_hist_eTmiss, "Et_miss", 20, 0., 1000.);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {

      Particles veto_e = apply<IdentifiedFinalState>(event, "veto_elecs").particles();
      if (!veto_e.empty()) {
        MSG_DEBUG("electrons in veto region");
        vetoEvent;
      }


      Jets cand_jets = apply<FastJets>(event, "AntiKtJets04")
                           .jetsByPt(Cuts::pT > 20 * GeV && Cuts::abseta < 4.9);
      Particles cand_e = apply<IdentifiedFinalState>(event, "elecs").particlesByPt();

      Particles cand_mu;
      Particles chg_tracks = apply<ChargedFinalState>(event, "cfs").particles();
      for (const Particle& mu : apply<IdentifiedFinalState>(event, "muons").particlesByPt()) {
        double pTinCone = -mu.pT();
        for (const Particle& track : chg_tracks) {
          if (deltaR(mu, track) <= 0.2) pTinCone += track.pT();
        }
        if (pTinCone < 1.8 * GeV) cand_mu.push_back(mu);
      }

      Jets cand_jets_2;
      for (const Jet& jet : cand_jets) {
        if (jet.abseta() >= 2.5)
          cand_jets_2.push_back(jet);
        else {
          bool away_from_e = true;
          for (const Particle& e : cand_e) {
            if (deltaR(e, jet) <= 0.2) {
              away_from_e = false;
              break;
            }
          }
          if (away_from_e) cand_jets_2.push_back(jet);
        }
      }

      Particles recon_e, recon_mu;
      for (const Particle& e : cand_e) {
        bool away = true;
        for (const Jet& jet : cand_jets_2) {
          if (deltaR(e, jet) < 0.4) {
            away = false;
            break;
          }
        }
        if (away) recon_e.push_back(e);
      }

      for (const Particle& mu : cand_mu) {
        bool away = true;
        for (const Jet& jet : cand_jets_2) {
          if (deltaR(mu, jet) < 0.4) {
            away = false;
            break;
          }
        }
        if (away) recon_mu.push_back(mu);
      }


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


      // final jet filter
      Jets recon_jets;
      for (const Jet& jet : cand_jets_2) {
        if (jet.abseta() <= 2.5) recon_jets.push_back(jet);
      }


      // now only use recon_jets, recon_mu, recon_e

      if (!(recon_mu.empty() && recon_e.empty())) {
        MSG_DEBUG("Charged leptons left after selection");
        vetoEvent;
      }

      if (eTmiss <= 100 * GeV) {
        MSG_DEBUG("Not enough eTmiss: " << eTmiss << " < 100");
        vetoEvent;
      }


      if (recon_jets.empty() || recon_jets[0].pT() <= 120.0 * GeV) {
        MSG_DEBUG("No hard leading jet in " << recon_jets.size() << " jets");
        vetoEvent;
      }

      // ==================== observables ====================

      // Njets, min_dPhi

      int Njets = 0;
      double min_dPhi = 999.999;
      double pTmiss_phi = pTmiss.phi();
      for (const Jet& jet : recon_jets) {
        if (jet.pT() > 40 * GeV) {
          if (Njets < 3) min_dPhi = min(min_dPhi, deltaPhi(pTmiss_phi, jet.phi()));
          ++Njets;
        }
      }

      if (Njets < 2) {
        MSG_DEBUG("Only " << Njets << " >40 GeV jets left");
        vetoEvent;
      }

      if (min_dPhi <= 0.4) {
        MSG_DEBUG("dPhi too small");
        vetoEvent;
      }

      // m_eff

      double m_eff_2j = eTmiss + recon_jets[0].pT() + recon_jets[1].pT();

      double m_eff_3j = recon_jets.size() < 3 ? -999.0 : m_eff_2j + recon_jets[2].pT();

      // etmiss / m_eff

      double et_meff_2j = eTmiss / m_eff_2j;
      double et_meff_3j = eTmiss / m_eff_3j;

      FourMomentum a = recon_jets[0].momentum();
      FourMomentum b = recon_jets[1].momentum();

      double m_T2 = mT2(a, b, pTmiss, 0.0); // zero mass invisibles


      // ==================== FILL ====================

      MSG_DEBUG("Trying to fill " << Njets << ' ' << m_eff_2j << ' ' << et_meff_2j << ' ' << m_eff_3j << ' '
                                  << et_meff_3j << ' ' << m_T2);

      _hist_eTmiss->fill(eTmiss);

      // AAAAAAAAAA
      if (et_meff_2j > 0.3) {
        _hist_meff_A->fill(m_eff_2j);
        if (m_eff_2j > 500 * GeV) {
          MSG_DEBUG("Hits A");
          _count_A->fill(0.5);
        }
      }

      // BBBBBBBBBB
      _hist_mT2_B->fill(m_T2);
      if (m_T2 > 300 * GeV) {
        MSG_DEBUG("Hits B");
        _count_B->fill(0.5);
      }

      // need 3 jets for C and D
      if (Njets >= 3 && et_meff_3j > 0.25) {

        _hist_meff_CD->fill(m_eff_3j);

        // CCCCCCCCCC
        if (m_eff_3j > 500 * GeV) {
          MSG_DEBUG("Hits C");
          _count_C->fill(0.5);
        }

        // DDDDDDDDDD
        if (m_eff_3j > 1000 * GeV) {
          MSG_DEBUG("Hits D");
          _count_D->fill(0.5);
        }
      }
    }

    /// @}

    void finalize() {

      double norm = crossSection() / picobarn * 35.0 / sumOfWeights();
      scale(_hist_meff_A, 100. * norm);
      scale(_hist_mT2_B, 100. * norm);
      scale(_hist_meff_CD, 40. * norm);
      scale(_hist_eTmiss, 50. * norm);
    }


  private:

    /// @name Histograms
    /// @{
    Histo1DPtr _count_A;
    Histo1DPtr _count_B;
    Histo1DPtr _count_C;
    Histo1DPtr _count_D;
    Histo1DPtr _hist_meff_A;
    Histo1DPtr _hist_mT2_B;
    Histo1DPtr _hist_meff_CD;
    Histo1DPtr _hist_eTmiss;
    /// @}
  };


  RIVET_DECLARE_ALIASED_PLUGIN(ATLAS_2011_I890749, ATLAS_2011_S8983313);

}