Rivet analyses

title: DELPHI_2000_I522656

Events shapes at MZ as function of thrust direction

Experiment: DELPHI (LEP)

Inspire ID: 522656

Status: VALIDATED

Authors: - Peter Richardson

References: - Eur.Phys.J.C 14 (2000) 557-584, 2000

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - e+ e- to hadrons

Measurement of event shapes for different ranges of the angle between the thrust axis and the beam. Jet rate using a mass measure or the Geneva algorithm are not implemented.

Source code:DELPHI_2000_I522656.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/Hemispheres.hh"

include "Rivet/Projections/ParisiTensor.hh"

include "Rivet/Projections/Sphericity.hh"

include "Rivet/Projections/Thrust.hh"

include "fastjet/EECambridgePlugin.hh"

namespace Rivet {

/// @brief event shapes vs thrust direction class DELPHI_2000_I522656 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(DELPHI_2000_I522656);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections.
  declare(Beam(), "Beams");
  const FinalState fs;
  declare(fs, "FS");
  const Thrust thrust(fs);
  declare(thrust, "Thrust");
  declare(Sphericity(fs), "Sphericity");
  declare(ParisiTensor(fs), "Parisi");
  declare(Hemispheres(thrust), "Hemispheres");
  declare(FastJets(fs, JetAlg::DURHAM, 0.7), "DurhamJets");
  declare(FastJets(fs, JetAlg::JADE), "JadeJets");

  // book histograms
  vector<double> bins = {0.00, 0.12, 0.24, 0.36, 0.48, 0.60, 0.72, 0.84, 0.96};
  book(_h_EEC, bins);
  book(_h_AEEC, bins);
  book(_h_cone, bins);
  book(_h_thrust, {0.12, 0.24, 0.36});
  // thrust angle binned
  size_t iy = 1, ioff = 0;
  for (size_t ix = 0; ix < _h_EEC->numBins(); ++ix) {
    book(_h_EEC->bin(ix + 1), 21 + ioff, 1, iy);
    book(_h_AEEC->bin(ix + 1), 25 + ioff, 1, iy);
    book(_h_cone->bin(ix + 1), 29 + ioff, 1, iy);
    if (ioff == 0) {
      book(_h_thrust->bin(iy), 33, 1, iy);
    }
    ++iy;
    if (iy == 3) {
      ++ioff;
      iy = 1;
    }
  }
  // total values
  book(_h_EEC_all, 3, 1, 1);
  book(_h_AEEC_all, 4, 1, 1);
  book(_h_cone_all, 5, 1, 1);
  book(_h_thrust_all, 6, 1, 1);
  book(_h_Oblateness, 7, 1, 1);
  book(_h_C, 8, 1, 1);
  book(_h_heavy, 9, 1, 1);
  book(_h_sum, 10, 1, 1);
  book(_h_diff, 11, 1, 1);
  book(_h_wide, 12, 1, 1);
  book(_h_total, 13, 1, 1);
  book(_h_jade, 17, 1, 1);
  book(_h_dur, 18, 1, 1);
  book(_h_cam, 20, 1, 1);
  book(_h_bin, "/TMP/hbin", bins);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& fs = apply<FinalState>(event, "FS");
  if (fs.particles().size() < 2) vetoEvent;
  // Get beams and average beam momentum
  const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
  // thrust
  const Thrust& thrust = apply<Thrust>(event, "Thrust");
  // angle bettwen thrust and beam
  double cosThrust = abs(beams.first.p3().unit().dot(thrust.thrustAxis()));
  _h_bin->fill(cosThrust);
  // thrust and related
  _h_thrust_all->fill(1. - thrust.thrust());
  _h_thrust->fill(cosThrust, 1. - thrust.thrust());
  _h_Oblateness->fill(thrust.oblateness());

  // visible energy and make pseudojets
  double Evis = 0.0;
  PseudoJets pjs;
  for (const Particle& p : fs.particles()) {
    Evis += p.E();
    fastjet::PseudoJet pj = p;
    pjs.push_back(pj);
  }
  double Evis2 = sqr(Evis);
  // (A)EEC
  // Need iterators since second loop starts at current outer loop iterator, i.e. no "foreach" here!
  for (Particles::const_iterator p_i = fs.particles().begin(); p_i != fs.particles().end(); ++p_i) {
    for (Particles::const_iterator p_j = p_i; p_j != fs.particles().end(); ++p_j) {
      if (p_i == p_j) continue;
      const Vector3 mom3_i = p_i->momentum().p3();
      const Vector3 mom3_j = p_j->momentum().p3();
      const double energy_i = p_i->momentum().E();
      const double energy_j = p_j->momentum().E();
      const double thetaij = 180. * mom3_i.unit().angle(mom3_j.unit()) / M_PI;
      double eec = (energy_i * energy_j) / Evis2;
      eec *= 2.;
      _h_EEC_all->fill(thetaij, eec);
      _h_EEC->fill(cosThrust, thetaij, eec);
      if (thetaij < 90.) {
        _h_AEEC_all->fill(thetaij, -eec);
        _h_AEEC->fill(cosThrust, thetaij, -eec);
      }
      else {
        _h_AEEC_all->fill(180. - thetaij, eec);
        _h_AEEC->fill(cosThrust, 180. - thetaij, eec);
      }
    }
  }
  // hemisphere related
  const Hemispheres& hemi = apply<Hemispheres>(event, "Hemispheres");
  _h_heavy->fill(hemi.scaledM2high());
  _h_diff->fill(hemi.scaledM2diff());
  _h_sum->fill(hemi.scaledM2low() + hemi.scaledM2high());
  _h_wide->fill(hemi.Bmax());
  _h_total->fill(hemi.Bsum());
  // C-parameter
  const ParisiTensor& parisi = apply<ParisiTensor>(event, "Parisi");
  _h_C->fill(parisi.C());
  // jets
  const FastJets& durjet = apply<FastJets>(event, "DurhamJets");
  const FastJets& jadejet = apply<FastJets>(event, "JadeJets");
  if (durjet.clusterSeq()) _h_dur->fill(durjet.clusterSeq()->exclusive_ymerge_max(2));
  if (jadejet.clusterSeq()) _h_jade->fill(jadejet.clusterSeq()->exclusive_ymerge_max(2));
  // Cambridge is more complicated, inclusive defn
  for (size_t i = 0; i < _h_cam->numBins(); ++i) {
    double ycut = _h_cam->bin(i).xMax();
    // double width = _h_y_2_Cambridge->bin(i).xWidth();
    fastjet::EECambridgePlugin plugin(ycut);
    fastjet::JetDefinition jdef(&plugin);
    fastjet::ClusterSequence cseq(pjs, jdef);
    unsigned int njet = cseq.inclusive_jets().size();
    if (njet == 2) {
      _h_cam->fill(_h_cam->bin(i).xMid());
      break;
    }
  }
  // jet cone
  Vector3 jetAxis = thrust.thrustAxis();
  if (hemi.highMassDirection()) jetAxis *= -1.;
  for (const Particle& p : fs.particles()) {
    const double thetaij = 180. * jetAxis.angle(p.p3().unit()) / M_PI;
    double jcef = p.E() / Evis;
    _h_cone_all->fill(thetaij, jcef);
    _h_cone->fill(cosThrust, thetaij, jcef);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (size_t ix = 0; ix < _h_EEC->numBins(); ++ix) {
    if (ix < 2) scale(_h_thrust->bin(ix + 1), 1. / _h_bin->bin(ix + 1).sumW());
    scale(_h_EEC->bin(ix + 1), 180. / M_PI / _h_bin->bin(ix + 1).sumW());
    scale(_h_AEEC->bin(ix + 1), 180. / M_PI / _h_bin->bin(ix + 1).sumW());
    scale(_h_cone->bin(ix + 1), 180. / M_PI / _h_bin->bin(ix + 1).sumW());
  }

  scale(_h_thrust_all, 1. / sumOfWeights());
  scale(_h_EEC_all, 180. / M_PI / sumOfWeights());
  scale(_h_AEEC_all, 180. / M_PI / sumOfWeights());
  scale(_h_cone_all, 180. / M_PI / sumOfWeights());
  scale(_h_Oblateness, 1. / sumOfWeights());
  scale(_h_C, 1. / sumOfWeights());
  scale(_h_heavy, 1. / sumOfWeights());
  scale(_h_sum, 1. / sumOfWeights());
  scale(_h_diff, 1. / sumOfWeights());
  scale(_h_wide, 1. / sumOfWeights());
  scale(_h_total, 1. / sumOfWeights());
  scale(_h_dur, 1. / sumOfWeights());
  scale(_h_jade, 1. / sumOfWeights());
  scale(_h_cam, 1. / sumOfWeights());
}

///@}


/// @name Histograms
///@{
Histo1DPtr _h_thrust_all, _h_EEC_all, _h_AEEC_all, _h_cone_all;
Histo1DPtr _h_Oblateness, _h_C, _h_heavy, _h_sum, _h_diff, _h_wide, _h_total;
Histo1DPtr _h_jade, _h_dur, _h_cam;
Histo1DGroupPtr _h_thrust, _h_EEC, _h_AEEC, _h_cone;
Histo1DPtr _h_bin;
///@}

};

RIVET_DECLARE_PLUGIN(DELPHI_2000_I522656);

} ```