Rivet analyses

title: CMS_2012_I941555

Measurement of differential $Z/\gamma^*$ $p_T$ and y

Experiment: CMS (LHC)

Inspire ID: 941555

Status: VALIDATED

Authors: - Luca Perrozzi - Justin Hugon

References: - Phys.Rev. D85 (2012) 032002 - arXiv: 1110.4973 - Expt page: CMS-EWK-10-010 - CERN-PH-EP-2011-169

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - $p p \to \mu^+ \mu^-$+X 7 TeV. Needs mass cut on lepton pair to avoid photon singularity, restrict $Z/\gamma^*$ mass range to roughly $50~\text{GeV}/c^2 < m_{\mu\mu} < 130~\text{GeV}/c^2$ for efficiency. Result is corrected for QED FSR (i.e. leptons are dressed), so turn off in generator.

Cross section as a function of $p_T$ and y of the Z boson decaying into muons in p p collisions at $\sqrt{s}$ = 7 TeV. $p_T$ and y cross sections are measured for $60 < m_{\mu\mu} < 120$ GeV. The $p_T$ cross section is measured for lepton $p_T > 20$ GeV and $\eta < 2.1$, while the y cross section is extrapolated to all lepton $p_T$ and $\eta$. This measurement was performed using 36 pb$^{-1}$ of data collected during 2010 with the CMS detector at the LHC.

Source code:CMS_2012_I941555.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DileptonFinder.hh"

namespace Rivet {

/// @brief CMS Z pT and rapidity in Drell-Yan events at 7 TeV /// /// @author Justin Hugon, Luca Perrozzi class CMS_2012_I941555 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2012_I941555);


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

void init() {

  // Set up projections
  /// @todo Really?: was DileptonFinder zfinder_dressed_mu_pt(-2.1, 2.1, 20, PID::MUON, 60*GeV, 120*GeV, 0.2, false, true);
  Cut cuts = Cuts::abseta < 2.1 && Cuts::pT > 20 * GeV;
  DileptonFinder zfinder_dressed_mu_pt(91.2 * GeV, 0.2, cuts && Cuts::abspid == PID::MUON,
                                       Cuts::massIn(60 * GeV, 120 * GeV));
  declare(zfinder_dressed_mu_pt, "DileptonFinder_dressed_mu_pt");
  DileptonFinder zfinder_dressed_el_pt(91.2 * GeV, 0.1, cuts && Cuts::abspid == PID::ELECTRON,
                                       Cuts::massIn(60 * GeV, 120 * GeV));
  declare(zfinder_dressed_el_pt, "DileptonFinder_dressed_el_pt");

  DileptonFinder zfinder_dressed_mu_rap(91.2 * GeV, 0.1, Cuts::abspid == PID::MUON,
                                        Cuts::massIn(60 * GeV, 120 * GeV));
  declare(zfinder_dressed_mu_rap, "DileptonFinder_dressed_mu_rap");
  DileptonFinder zfinder_dressed_el_rap(91.2 * GeV, 0.1, Cuts::abspid == PID::ELECTRON,
                                        Cuts::massIn(60 * GeV, 120 * GeV));
  declare(zfinder_dressed_el_rap, "DileptonFinder_dressed_el_rap");

  // Book histograms
  book(_hist_zrap_mu_dressed, 1, 1, 1);   // muon "dressed" rapidity
  book(_hist_zrap_el_dressed, 1, 1, 2);   // electron "dressed" rapidity
  book(_hist_zrap_comb_dressed, 1, 1, 3); // electron "dressed" rapidity

  book(_hist_zpt_mu_dressed, 2, 1, 1);   // muon "dressed" pt
  book(_hist_zpt_el_dressed, 2, 1, 2);   // electron "dressed" pt
  book(_hist_zpt_comb_dressed, 2, 1, 3); // electron "dressed" pt

  book(_hist_zptpeak_mu_dressed, 3, 1, 1);   // muon "dressed" pt peak
  book(_hist_zptpeak_el_dressed, 3, 1, 2);   // electron "dressed" pt peak
  book(_hist_zptpeak_comb_dressed, 3, 1, 3); // electron "dressed" pt peak
}


/// Do the analysis
void analyze(const Event& evt) {

  const DileptonFinder& zfinder_dressed_mu_rap = apply<DileptonFinder>(evt,
                                                                       "DileptonFinder_dressed_mu_rap");
  if (!zfinder_dressed_mu_rap.bosons().empty()) {
    const FourMomentum pZ = zfinder_dressed_mu_rap.bosons()[0].momentum();
    _hist_zrap_mu_dressed->fill(pZ.absrapidity());
    _hist_zrap_comb_dressed->fill(pZ.absrapidity());
  }

  const DileptonFinder& zfinder_dressed_mu_pt = apply<DileptonFinder>(evt,
                                                                      "DileptonFinder_dressed_mu_pt");
  if (!zfinder_dressed_mu_pt.bosons().empty()) {
    const FourMomentum pZ = zfinder_dressed_mu_pt.bosons()[0].momentum();
    _hist_zpt_mu_dressed->fill(pZ.pT() / GeV);
    _hist_zpt_comb_dressed->fill(pZ.pT() / GeV);
    if (pZ.pT() < 30 * GeV) {
      _hist_zptpeak_mu_dressed->fill(pZ.pT() / GeV);
      _hist_zptpeak_comb_dressed->fill(pZ.pT() / GeV);
    }
  }

  const DileptonFinder& zfinder_dressed_el_rap = apply<DileptonFinder>(evt,
                                                                       "DileptonFinder_dressed_el_rap");
  if (!zfinder_dressed_el_rap.bosons().empty()) {
    const FourMomentum pZ = zfinder_dressed_el_rap.bosons()[0].momentum();
    _hist_zrap_el_dressed->fill(abs(pZ.rapidity() / GeV));
    _hist_zrap_comb_dressed->fill(abs(pZ.rapidity() / GeV));
  }

  const DileptonFinder& zfinder_dressed_el_pt = apply<DileptonFinder>(evt,
                                                                      "DileptonFinder_dressed_el_pt");
  if (!zfinder_dressed_el_pt.bosons().empty()) {
    const FourMomentum pZ = zfinder_dressed_el_pt.bosons()[0].momentum();
    _hist_zpt_el_dressed->fill(pZ.pT() / GeV);
    _hist_zpt_comb_dressed->fill(pZ.pT() / GeV);
    if (pZ.pT() < 30 * GeV) {
      _hist_zptpeak_el_dressed->fill(pZ.pT() / GeV);
      _hist_zptpeak_comb_dressed->fill(pZ.pT() / GeV);
    }
  }
}


void finalize() {
  normalize(_hist_zrap_mu_dressed);
  normalize(_hist_zpt_mu_dressed);
  normalize(_hist_zptpeak_mu_dressed);

  normalize(_hist_zrap_el_dressed);
  normalize(_hist_zpt_el_dressed);
  normalize(_hist_zptpeak_el_dressed);

  normalize(_hist_zrap_comb_dressed);
  normalize(_hist_zpt_comb_dressed);
  normalize(_hist_zptpeak_comb_dressed);
}

/// @}

private:

Histo1DPtr _hist_zrap_mu_dressed;
Histo1DPtr _hist_zpt_mu_dressed;
Histo1DPtr _hist_zptpeak_mu_dressed;

Histo1DPtr _hist_zrap_el_dressed;
Histo1DPtr _hist_zpt_el_dressed;
Histo1DPtr _hist_zptpeak_el_dressed;

Histo1DPtr _hist_zrap_comb_dressed;
Histo1DPtr _hist_zpt_comb_dressed;
Histo1DPtr _hist_zptpeak_comb_dressed;

};

RIVET_DECLARE_PLUGIN(CMS_2012_I941555);

} ```