Rivet analyses

title: D0_2008_I792812

Measurement of differential $Z/\gamma^*$ + 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: - $p \bar{p} \to \mu^+ \mu^-$ + jets at 1960~GeV. Needs mass cut on lepton pair to avoid photon singularity, looser than $65 < m_{\mu\mu} < 115$ 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 $p \bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV, based on an integrated luminosity of 1.0 fb$^{-1}$.

Source code:D0_2008_I792812.cc

```c++ // -- 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