Rivet analyses

Monte Carlo validation observables for Z[ℓ+ ℓ−] production

Experiment: ()

Status: VALIDATED

Authors: - Frank Siegert - Christian Gutschow

References: none listed

Beams: * *

Beam energies: ANY

Run details: - ℓ+ℓ− analysis. Needs mass cut on lepton pair to avoid photon singularity, e.g. a min range of 66 < mll < 116 GeV

Monte Carlo validation observables for Z[ℓ+ ℓ−] production

Source code:MC_ZINC.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DileptonFinder.hh"

namespace Rivet {


  /// @brief MC validation analysis for Z events
  class MC_ZINC : public Analysis {
  public:

    /// Default constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(MC_ZINC);

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

    /// Book histograms
    void init() {
      _dR = 0.2;
      if (getOption("SCHEME") == "BARE") _dR = 0.0;
      _lepton = PID::ELECTRON;
      if (getOption("LMODE") == "MU") _lepton = PID::MUON;

      // set FS cuts from input options
      const double etacut = getOption<double>("ABSETALMAX", 3.5);
      const double ptcut = getOption<double>("PTLMIN", 25.);

      Cut cut = Cuts::abseta < etacut && Cuts::pT > ptcut * GeV;
      DileptonFinder zfinder(91.2 * GeV, _dR, cut && Cuts::abspid == _lepton,
                             Cuts::massIn(66.0 * GeV, 116.0 * GeV));
      declare(zfinder, "DileptonFinder");

      book(_h_Z_mass, "Z_mass", 50, 66.0, 116.0);
      book(_h_Z_pT, "Z_pT", logspace(100, 1.0, 0.5 * (sqrtS() > 0. ? sqrtS() : 14000.) / GeV));
      book(_h_Z_pT_peak, "Z_pT_peak", 25, 0.0, 25.0);
      book(_h_Z_y, "Z_y", 40, -4.0, 4.0);
      book(_h_Z_phi, "Z_phi", 25, 0.0, TWOPI);
      book(_h_lepton_pT, "lepton_pT", logspace(100, 10.0, 0.25 * (sqrtS() > 0. ? sqrtS() : 14000.) / GeV));
      book(_h_lepton_eta, "lepton_eta", 40, -4.0, 4.0);
    }


    /// Do the analysis
    void analyze(const Event& e) {
      const DileptonFinder& zfinder = apply<DileptonFinder>(e, "DileptonFinder");
      if (zfinder.bosons().size() != 1) vetoEvent;

      FourMomentum zmom(zfinder.bosons()[0].momentum());
      _h_Z_mass->fill(zmom.mass() / GeV);
      _h_Z_pT->fill(zmom.pT() / GeV);
      _h_Z_pT_peak->fill(zmom.pT() / GeV);
      _h_Z_y->fill(zmom.rapidity());
      _h_Z_phi->fill(zmom.phi());
      for (const Particle& l : zfinder.constituents()) {
        _h_lepton_pT->fill(l.pT() / GeV);
        _h_lepton_eta->fill(l.eta());
      }
    }


    /// Finalize
    void finalize() {
      const double s = crossSection() / picobarn / sumOfWeights();
      scale(_h_Z_mass, s);
      scale(_h_Z_pT, s);
      scale(_h_Z_pT_peak, s);
      scale(_h_Z_y, s);
      scale(_h_Z_phi, s);
      scale(_h_lepton_pT, s);
      scale(_h_lepton_eta, s);
    }

    /// @}


  protected:

    /// @name Parameters for specialised e/mu and dressed/bare subclassing
    /// @{
    double _dR;
    PdgId _lepton;
    /// @}


  private:

    /// @name Histograms
    /// @{
    Histo1DPtr _h_Z_mass;
    Histo1DPtr _h_Z_pT;
    Histo1DPtr _h_Z_pT_peak;
    Histo1DPtr _h_Z_y;
    Histo1DPtr _h_Z_phi;
    Histo1DPtr _h_lepton_pT;
    Histo1DPtr _h_lepton_eta;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(MC_ZINC);

}