Rivet analyses

title: ATLAS_2011_I917931

Measurement of the Z pT with electrons and muons at 7 TeV

Experiment: ATLAS (LHC)

Inspire ID: 917931

Status: VALIDATED

Authors: - Elena Yatsenko - Judith Katzy

References: - Expt page: ATLAS-STDM-2011-09 - arXiv: 1107.2381

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - Run with inclusive $Z$ events, with $Z/\gamma^*$ decays to electrons and/or muons.

The Z pT at $\sqrt{s} = 7$~TeV is measured using electron and muon $Z$ decay channels. The dressed leptons definition uses photons clustered in a cone around the charged leptons, while the bare lepton definition uses the post-FSR charged leptons only in the $Z$ reconstruction. The data used in the bare leptons calculation are based on a forward application of a PHOTOS-based energy loss correction and are hence not quite model-independent.

Source code:ATLAS_2011_I917931.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DileptonFinder.hh"

namespace Rivet {

/// @brief ATLAS Z pT in Drell-Yan events at 7 TeV /// /// @author Elena Yatsenko, Judith Katzy class ATLAS_2011_I917931 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2011_I917931);


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

void init() {

  // Set up projections
  Cut cut = Cuts::abseta < 2.4 && Cuts::pT > 20 * GeV;
  DileptonFinder zfinder_dressed_el(91.2 * GeV, 0.1, cut && Cuts::abspid == PID::ELECTRON,
                                    Cuts::massIn(66.0 * GeV, 116.0 * GeV));
  declare(zfinder_dressed_el, "DileptonFinder_dressed_el");
  DileptonFinder zfinder_bare_el(91.2 * GeV, 0.0, cut && Cuts::abspid == PID::ELECTRON,
                                 Cuts::massIn(66.0 * GeV, 116.0 * GeV));
  declare(zfinder_bare_el, "DileptonFinder_bare_el");
  DileptonFinder zfinder_dressed_mu(91.2 * GeV, 0.1, cut && Cuts::abspid == PID::MUON,
                                    Cuts::massIn(66.0 * GeV, 116.0 * GeV));
  declare(zfinder_dressed_mu, "DileptonFinder_dressed_mu");
  DileptonFinder zfinder_bare_mu(91.2 * GeV, 0.0, cut && Cuts::abspid == PID::MUON,
                                 Cuts::massIn(66.0 * GeV, 116.0 * GeV));
  declare(zfinder_bare_mu, "DileptonFinder_bare_mu");

  // Book histograms
  book(_hist_zpt_el_dressed, 1, 1, 2); // electron "dressed"
  book(_hist_zpt_el_bare, 1, 1, 3);    // electron "bare"
  book(_hist_zpt_mu_dressed, 2, 1, 2); // muon "dressed"
  book(_hist_zpt_mu_bare, 2, 1, 3);    // muon "bare"

  book(_sumw_el_bare, "_sumw_el_bare");
  book(_sumw_el_dressed, "_sumw_el_dressed");
  book(_sumw_mu_bare, "_sumw_mu_bare");
  book(_sumw_mu_dressed, "_sumw_mu_dressed");
}


/// Do the analysis
void analyze(const Event& evt) {
  const DileptonFinder& zfinder_dressed_el = apply<DileptonFinder>(evt, "DileptonFinder_dressed_el");
  if (!zfinder_dressed_el.bosons().empty()) {
    _sumw_el_dressed->fill();
    const FourMomentum pZ = zfinder_dressed_el.bosons()[0].momentum();
    _hist_zpt_el_dressed->fill(pZ.pT() / GeV);
  }

  const DileptonFinder& zfinder_bare_el = apply<DileptonFinder>(evt, "DileptonFinder_bare_el");
  if (!zfinder_bare_el.bosons().empty()) {
    _sumw_el_bare->fill();
    const FourMomentum pZ = zfinder_bare_el.bosons()[0].momentum();
    _hist_zpt_el_bare->fill(pZ.pT() / GeV);
  }

  const DileptonFinder& zfinder_dressed_mu = apply<DileptonFinder>(evt, "DileptonFinder_dressed_mu");
  if (!zfinder_dressed_mu.bosons().empty()) {
    _sumw_mu_dressed->fill();
    const FourMomentum pZ = zfinder_dressed_mu.bosons()[0].momentum();
    _hist_zpt_mu_dressed->fill(pZ.pT() / GeV);
  }

  const DileptonFinder& zfinder_bare_mu = apply<DileptonFinder>(evt, "DileptonFinder_bare_mu");
  if (!zfinder_bare_mu.bosons().empty()) {
    _sumw_mu_bare->fill();
    const FourMomentum pZ = zfinder_bare_mu.bosons()[0].momentum();
    _hist_zpt_mu_bare->fill(pZ.pT() / GeV);
  }
}


void finalize() {
  if (_sumw_el_dressed->val() != 0) scale(_hist_zpt_el_dressed, 1 / *_sumw_el_dressed);
  if (_sumw_el_bare->val() != 0) scale(_hist_zpt_el_bare, 1 / *_sumw_el_bare);
  if (_sumw_mu_dressed->val() != 0) scale(_hist_zpt_mu_dressed, 1 / *_sumw_mu_dressed);
  if (_sumw_mu_bare->val() != 0) scale(_hist_zpt_mu_bare, 1 / *_sumw_mu_bare);
}

/// @}

private:

CounterPtr _sumw_el_bare, _sumw_el_dressed;
CounterPtr _sumw_mu_bare, _sumw_mu_dressed;

Histo1DPtr _hist_zpt_el_dressed;
Histo1DPtr _hist_zpt_el_bare;
Histo1DPtr _hist_zpt_mu_dressed;
Histo1DPtr _hist_zpt_mu_bare;

};

RIVET_DECLARE_ALIASED_PLUGIN(ATLAS_2011_I917931, ATLAS_2011_S9131140);

} ```

Aliases: - ATLAS_2011_S9131140