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/Sphericity.hh"

namespace Rivet {


  /// @brief 3 jet events at 29 GeV
  class MARKII_1985_I216850 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(MARKII_1985_I216850);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      const FinalState fs;
      declare(fs, "FS");
      const ChargedFinalState cfs;
      declare(cfs, "CFS");
      Sphericity sphere(fs);
      declare(sphere, "Sphericity");
      FastJets jadeJets = FastJets(fs, JetAlg::JADE, -1, JetMuons::ALL, JetInvisibles::DECAY);
      declare(jadeJets, "JadeJets");
      // histos
      book(_h, 1, 1, 1);
      book(_njet, "TMP/njet");
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // at least 5 charged particles
      const FinalState& cfs = apply<FinalState>(event, "CFS");
      if (cfs.particles().size() < 5) vetoEvent;
      // sphericity cuts
      const Sphericity& sphericity = apply<Sphericity>(event, "Sphericity");
      if (sphericity.lambda3() < 0.06 || sphericity.lambda2() - sphericity.lambda3() < 0.05) vetoEvent;
      // cluster particles using jet
      const FastJets& jadejet = apply<FastJets>(event, "JadeJets");
      Particles fs = apply<FinalState>(event, "FS").particles();
      PseudoJets pjets = jadejet.clusterSeq()->exclusive_jets(3);
      Jets jets = jadejet.mkJets(pjets, fs);
      Vector3 n[3];
      // loop over the jets
      for (unsigned int ix = 0; ix < jets.size(); ++ix) {
        if (jets[ix].constituents().size() < 3) vetoEvent;
        double energy = 0.;
        for (const Particle& p : jets[ix].constituents()) energy += p.E();
        if (energy < 2. * GeV) vetoEvent;
        n[ix] = jets[ix].mom().p3().unit();
      }
      vector<double> dot;
      dot.reserve(3);
      for (unsigned int ix = 0; ix < jets.size(); ++ix) {
        for (unsigned int iy = ix + 1; iy < jets.size(); ++iy) {
          dot.push_back(n[ix].dot(n[iy]));
          const double angle = acos(dot.back()) * 180. / M_PI;
          if (angle < 100 || angle > 140) vetoEvent;
        }
      }
      double Ejet[3];
      Ejet[0] = (sqrtS() * (dot[1] - dot[0] * dot[2])) / ((-1 + dot[0]) * (1 + dot[0] - dot[1] - dot[2]));
      Ejet[1] = (sqrtS() * (-(dot[0] * dot[1]) + dot[2])) / ((-1 + dot[0]) * (1 + dot[0] - dot[1] - dot[2]));
      Ejet[2] = (sqrtS() * (1 + dot[0])) / (1 + dot[0] - dot[1] - dot[2]);
      // now loop over jets
      for (unsigned int ix = 0; ix < 3; ++ix) {
        _njet->fill();
        for (const Particle& p : jets[ix].constituents()) {
          if (p.isCharged()) {
            _h->fill(p.momentum().p3().mod() / Ejet[ix]);
          }
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_h, 1. / *_njet);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h;
    CounterPtr _njet;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(MARKII_1985_I216850);

}