Rivet analyses

Measurement of differential Z/γ* + jet + X cross sections

Experiment: D0 (Tevatron Run 2)

Inspire ID: 792812

Status: VALIDATED

Authors: - Andy Buckley - Gavin Hesketh - Frank Siegert

References: - Phys.Lett. B669 (2008) 278-286 - DOI: 10.1016/j.physletb.2008.09.060 - arXiv: 0808.1296

Beams: p- p+

Beam energies: (980.0, 980.0)GeV

Run details: - pp̄ → μ+μ− + jets at 1960~GeV. Needs mass cut on lepton pair to avoid photon singularity, looser than 65 < mμμ < 115 GeV.

Cross sections as a function of pT and rapidity of the boson and pT and rapidity of the leading jet in the di-muon channel in pp̄ collisions at $\sqrt{s}$ = 1.96 TeV, based on an integrated luminosity of 1.0 fb−1.

Source code:D0_2008_I792812.cc

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

namespace Rivet {


  /// @brief D0 differential Z/\f$ \gamma^* \f$ + jet + \f$ X \f$ cross sections
  ///
  /// @author Gavin Hesketh, Andy Buckley, Frank Siegert
  class D0_2008_I792812 : public Analysis {
  public:

    RIVET_DEFAULT_ANALYSIS_CTOR(D0_2008_I792812);


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

    /// Book histograms
    void init() {

      Cut cut = Cuts::abseta < 1.7 && Cuts::pT > 15*GeV;
      DileptonFinder zfinder(91.2*GeV, 0.2, cut && Cuts::abspid == PID::MUON, Cuts::massIn(65*GeV, 115*GeV));
      declare(zfinder, "DileptonFinder");

      FastJets conefinder(zfinder.remainingFinalState(), JetAlg::D0ILCONE, 0.5);
      declare(conefinder, "ConeFinder");

      book(_sum_of_weights_inclusive, "sum_of_weights_inclusive");

      book(_h_jet_pT_cross_section ,1, 1, 1);
      book(_h_jet_pT_normalised ,1, 1, 2);
      book(_h_jet_y_cross_section ,2, 1, 1);
      book(_h_jet_y_normalised ,2, 1, 2);
      book(_h_Z_pT_cross_section ,3, 1, 1);
      book(_h_Z_pT_normalised ,3, 1, 2);
      book(_h_Z_y_cross_section ,4, 1, 1);
      book(_h_Z_y_normalised ,4, 1, 2);
      book(_h_total_cross_section ,5, 1, 1);
    }


    // Do the analysis
    void analyze(const Event& e) {
      const DileptonFinder& zfinder = apply<DileptonFinder>(e, "DileptonFinder");
      if (zfinder.bosons().size()==1) {
        _sum_of_weights_inclusive->fill();
        const JetFinder& jetpro = apply<JetFinder>(e, "ConeFinder");
        const Jets& jets = jetpro.jetsByPt(Cuts::pT > 20*GeV && Cuts::abseta < 2.8);

        // Return if there are no jets:
        if (jets.size() < 1) {
          MSG_DEBUG("Skipping event " << numEvents() << " because no jets pass cuts ");
          vetoEvent;
        }

        const FourMomentum Zmom = zfinder.bosons()[0].momentum();

        // In jet pT
        _h_jet_pT_cross_section->fill( jets[0].pT());
        _h_jet_pT_normalised->fill( jets[0].pT());
        _h_jet_y_cross_section->fill( fabs(jets[0].rapidity()));
        _h_jet_y_normalised->fill( fabs(jets[0].rapidity()));

        // In Z pT
        _h_Z_pT_cross_section->fill(Zmom.pT());
        _h_Z_pT_normalised->fill(Zmom.pT());
        _h_Z_y_cross_section->fill(Zmom.absrap());
        _h_Z_y_normalised->fill(Zmom.absrap());

        _h_total_cross_section->fill(1960);
      }
    }


    /// Finalize
    void finalize() {
      const double invlumi = crossSection()/picobarn/sumOfWeights();
      scale(_h_total_cross_section, invlumi);
      scale(_h_jet_pT_cross_section, invlumi);
      scale(_h_jet_y_cross_section, invlumi);
      scale(_h_Z_pT_cross_section, invlumi);
      scale(_h_Z_y_cross_section, invlumi);

      double factor=1/dbl(*_sum_of_weights_inclusive);
      if (_sum_of_weights_inclusive->val() == 0) factor = 0;
      scale(_h_jet_pT_normalised, factor);
      scale(_h_jet_y_normalised, factor);
      scale(_h_Z_pT_normalised, factor);
      scale(_h_Z_y_normalised, factor);
    }

    /// @}


  private:

    /// @name Histograms
    /// @{
    Histo1DPtr _h_jet_pT_cross_section;
    Histo1DPtr _h_jet_y_cross_section;
    Histo1DPtr _h_Z_pT_cross_section;
    Histo1DPtr _h_Z_y_cross_section;
    Histo1DPtr _h_total_cross_section;
    Histo1DPtr _h_jet_pT_normalised;
    Histo1DPtr _h_jet_y_normalised;
    Histo1DPtr _h_Z_pT_normalised;
    Histo1DPtr _h_Z_y_normalised;
    /// @}

    CounterPtr _sum_of_weights_inclusive;

  };


  RIVET_DECLARE_ALIASED_PLUGIN(D0_2008_I792812, D0_2008_S7863608);

}

Aliases: - D0_2008_S7863608