Rivet analyses

title: ATLAS_2011_CONF_2011_090

Single lepton search for supersymmetry

Experiment: ATLAS (LHC)

Inspire ID: 1204092

Status: OBSOLETE

Authors: - Angela Chen

References: - Expt page: ATLAS-CONF-2011-090

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - BSM signal events at 7000 GeV.

Single lepton search for supersymmmetric particles by ATLAS at 7 TeV. Event counts in electron and muon signal regions are implemented as one-bin histograms. Histograms for missing transverse energy and effective mass are implemented for the two signal regions.

Source code:ATLAS_2011_CONF_2011_090.cc

```c++ // -- 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_CONF_2011_090 : public Analysis { public:

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

/// Constructor

ATLAS_2011_CONF_2011_090()
    : Analysis("ATLAS_2011_CONF_2011_090") { }

/// @}

public:

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

/// Book histograms and initialize 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");

  // veto region electrons (from 2010 arXiv:1102.2357v2)
  Cut vetocut = Cuts::absetaIn(1.37, 1.52);
  IdentifiedFinalState veto_elecs(vetocut && Cuts::pT > 10 * GeV);
  veto_elecs.acceptIdPair(PID::ELECTRON);
  declare(veto_elecs, "veto_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, JetAlg::ANTIKT, 0.4), "AntiKtJets04");

  // all tracks (to do deltaR with leptons)
  declare(ChargedFinalState(Cuts::abseta < 3.0 && Cuts::pT > 0.5 * GeV), "cfs");

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

  /// Book histograms
  book(_count_mu_channel, "count_muon_channel", 1, 0., 1.);
  book(_count_e_channel, "count_electron_channel", 1, 0., 1.);
  book(_hist_eTmiss_e, "Et_miss_e", 50, 0., 500.);
  book(_hist_eTmiss_mu, "Et_miss_mu", 50, 0., 500.);
  book(_hist_m_eff_e, "m_eff_e", 60, 0., 1500.);
  book(_hist_m_eff_mu, "m_eff_mu", 60, 0., 1500.);
  book(_hist_m_eff_e_final, "m_eff_e_final", 15, 0., 1500.);
  book(_hist_m_eff_mu_final, "m_eff_mu_final", 15, 0., 1500.);
}


/// 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 < 2.8);

  Particles candtemp_e = apply<IdentifiedFinalState>(event, "elecs").particlesByPt();
  Particles candtemp_mu = apply<IdentifiedFinalState>(event, "muons").particlesByPt();
  Particles chg_tracks = apply<ChargedFinalState>(event, "cfs").particles();
  Particles cand_mu;
  Particles cand_e;

  // pTcone around muon track
  for (const Particle& mu : candtemp_mu) {
    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);
  }


  // pTcone around electron
  for (const Particle& e : candtemp_e) {
    double pTinCone = -e.pT();
    for (const Particle& track : chg_tracks) {
      if (deltaR(e, track) < 0.2) pTinCone += track.pT();
    }
    if (pTinCone < 0.10 * e.pT()) cand_e.push_back(e);
  }


  // discard jets that overlap with electrons
  Jets cand_jets_2;
  for (const Jet& jet : cand_jets) {
    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);
  }

  // only consider leptons far from jet
  Particles recon_e, recon_mu;
  for (const Particle& e : cand_e) {
    bool e_near_jet = false;
    for (const Jet& jet : cand_jets_2) {
      if (inRange(deltaR(e, jet), 0.2, 0.4)) e_near_jet = true;
    }
    if (!e_near_jet) recon_e.push_back(e);
  }

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


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


  // Njets

  int Njets = 0;
  double pTmiss_phi = pTmiss.phi();
  for (const Jet& jet : recon_jets) {
    if (jet.abseta() < 2.8) Njets += 1;
  }
  if (Njets < 3) {
    MSG_DEBUG("Only " << Njets << " jets w/ eta<2.8 left");
    vetoEvent;
  }

  if (recon_jets[0].pT() <= 60.0 * GeV) {
    MSG_DEBUG("No hard leading jet in " << recon_jets.size() << " jets");
    vetoEvent;
  }
  for (int i = 1; i < 3; ++i) {
    if (recon_jets[i].pT() <= 25 * GeV) {
      vetoEvent;
    }
  }

  for (int i = 0; i < 3; ++i) {
    double dPhi = deltaPhi(pTmiss_phi, recon_jets[i].phi());
    if (dPhi <= 0.2) {
      MSG_DEBUG("dPhi too small");
      vetoEvent;
      break;
    }
  }


  Particles lepton;
  if (recon_mu.empty() && recon_e.empty()) {
    MSG_DEBUG("No leptons");
    vetoEvent;
  }
  else {
    for (const Particle& mu : recon_mu) lepton.push_back(mu);
    for (const Particle& e : recon_e) lepton.push_back(e);
  }

  std::sort(lepton.begin(), lepton.end(), cmpMomByPt);

  double e_id = 11;
  double mu_id = 13;

  // one hard leading lepton cut
  if (lepton[0].abspid() == e_id && lepton[0].pT() <= 25 * GeV) {
    vetoEvent;
  }
  else if (lepton[0].abspid() == mu_id && lepton[0].pT() <= 20 * GeV) {
    vetoEvent;
  }

  // exactly one hard leading lepton cut
  if (lepton.size() > 1) {
    if (lepton[1].abspid() == e_id && lepton[1].pT() > 20 * GeV) {
      vetoEvent;
    }
    else if (lepton[1].abspid() == mu_id && lepton[1].pT() > 10 * GeV) {
      vetoEvent;
    }
  }


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


  FourMomentum pT_l = lepton[0].momentum();


  double dPhi = deltaPhi(pT_l.phi(), pTmiss_phi);
  double mT = sqrt(2 * pT_l.pT() * eTmiss * (1 - cos(dPhi)));


  // effective mass
  double m_eff = eTmiss + pT_l.pT() + recon_jets[0].pT() + recon_jets[1].pT() + recon_jets[2].pT();


  // Electron channel signal region

  if (lepton[0].abspid() == e_id) {

    _hist_eTmiss_e->fill(eTmiss);
    _hist_m_eff_e->fill(m_eff);

    if (mT > 100 * GeV && eTmiss > 125 * GeV) {
      _hist_m_eff_e_final->fill(m_eff);
      if (m_eff > 500 * GeV && eTmiss > 0.25 * m_eff) {
        _count_e_channel->fill(0.5);
      }
    }
  }

  // Muon channel signal region

  else if (lepton[0].abspid() == mu_id) {

    _hist_eTmiss_mu->fill(eTmiss);
    _hist_m_eff_mu->fill(m_eff);

    if (mT > 100 * GeV && eTmiss > 125 * GeV) {
      _hist_m_eff_mu_final->fill(m_eff);
      if (m_eff > 500 * GeV && eTmiss > 0.25 * m_eff) {
        _count_mu_channel->fill(0.5);
      }
    }
  }
}

/// @}


void finalize() {
  scale(_hist_eTmiss_e, 10. * 165. * crossSection() / picobarn / sumOfWeights());
  scale(_hist_eTmiss_mu, 10. * 165. * crossSection() / picobarn / sumOfWeights());
  scale(_hist_m_eff_e, 25. * 165. * crossSection() / picobarn / sumOfWeights());
  scale(_hist_m_eff_mu, 25. * 165. * crossSection() / picobarn / sumOfWeights());
  scale(_hist_m_eff_e_final, 100. * 165. * crossSection() / picobarn / sumOfWeights());
  scale(_hist_m_eff_mu_final, 100. * 165. * crossSection() / picobarn / sumOfWeights());
}

private:

/// @name Histograms
/// @{
Histo1DPtr _count_e_channel;
Histo1DPtr _count_mu_channel;

Histo1DPtr _hist_eTmiss_e;
Histo1DPtr _hist_eTmiss_mu;

Histo1DPtr _hist_m_eff_e;
Histo1DPtr _hist_m_eff_mu;
Histo1DPtr _hist_m_eff_e_final;
Histo1DPtr _hist_m_eff_mu_final;


/// @}

};

RIVET_DECLARE_PLUGIN(ATLAS_2011_CONF_2011_090);

} ```