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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
  • 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
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/ZFinder.hh"
  4
  5namespace Rivet {
  6
  7
  8  /// @brief CMS Z pT and rapidity in Drell-Yan events at 7 TeV
  9  /// @author Justin Hugon, Luca Perrozzi
 10  class CMS_2012_I941555 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    CMS_2012_I941555()
 15      : Analysis("CMS_2012_I941555")
 16    {
 17    }
 18
 19
 20    /// @name Analysis methods
 21    //@{
 22
 23    void init() {
 24
 25      // Set up projections
 26      /// @todo Really?: ZFinder zfinder_dressed_mu_pt(-2.1, 2.1, 20, PID::MUON, 60*GeV, 120*GeV, 0.2, false, true);
 27      FinalState fs;
 28      Cut cuts = Cuts::abseta < 2.1 && Cuts::pT > 20*GeV;
 29      ZFinder zfinder_dressed_mu_pt(fs, cuts, PID::MUON, 60*GeV, 120*GeV, 0.2);
 30      declare(zfinder_dressed_mu_pt, "ZFinder_dressed_mu_pt");
 31      ZFinder zfinder_dressed_el_pt(fs, cuts, PID::ELECTRON, 60*GeV, 120*GeV, 0.1);
 32      declare(zfinder_dressed_el_pt, "ZFinder_dressed_el_pt");
 33
 34      ZFinder zfinder_dressed_mu_rap(fs, Cuts::open(), PID::MUON, 60*GeV, 120*GeV, 0.1);
 35      declare(zfinder_dressed_mu_rap, "ZFinder_dressed_mu_rap");
 36      ZFinder zfinder_dressed_el_rap(fs, Cuts::open(), PID::ELECTRON, 60*GeV, 120*GeV, 0.1);
 37      declare(zfinder_dressed_el_rap, "ZFinder_dressed_el_rap");
 38
 39      // Book histograms
 40      book(_hist_zrap_mu_dressed      ,1, 1, 1);  // muon "dressed" rapidity
 41      book(_hist_zrap_el_dressed      ,1, 1, 2);  // electron "dressed" rapidity
 42      book(_hist_zrap_comb_dressed    ,1, 1, 3);  // electron "dressed" rapidity
 43
 44      book(_hist_zpt_mu_dressed       ,2, 1, 1);  // muon "dressed" pt
 45      book(_hist_zpt_el_dressed       ,2, 1, 2);  // electron "dressed" pt
 46      book(_hist_zpt_comb_dressed     ,2, 1, 3);  // electron "dressed" pt
 47
 48      book(_hist_zptpeak_mu_dressed   ,3, 1, 1);  // muon "dressed" pt peak
 49      book(_hist_zptpeak_el_dressed   ,3, 1, 2);  // electron "dressed" pt peak
 50      book(_hist_zptpeak_comb_dressed ,3, 1, 3);  // electron "dressed" pt peak
 51    }
 52
 53
 54    /// Do the analysis
 55    void analyze(const Event& evt) {
 56      const double weight = 1.0;
 57
 58      const ZFinder& zfinder_dressed_mu_rap = apply<ZFinder>(evt, "ZFinder_dressed_mu_rap");
 59      if (!zfinder_dressed_mu_rap.bosons().empty()) {
 60        const FourMomentum pZ = zfinder_dressed_mu_rap.bosons()[0].momentum();
 61        _hist_zrap_mu_dressed->fill(pZ.rapidity()/GeV, weight);
 62        _hist_zrap_comb_dressed->fill(pZ.rapidity()/GeV, weight);
 63      }
 64
 65      const ZFinder& zfinder_dressed_mu_pt = apply<ZFinder>(evt, "ZFinder_dressed_mu_pt");
 66      if (!zfinder_dressed_mu_pt.bosons().empty()) {
 67        const FourMomentum pZ = zfinder_dressed_mu_pt.bosons()[0].momentum();
 68        _hist_zpt_mu_dressed->fill(pZ.pT()/GeV, weight);
 69        _hist_zpt_comb_dressed->fill(pZ.pT()/GeV, weight);
 70        if (pZ.pT() < 30*GeV) {
 71          _hist_zptpeak_mu_dressed->fill(pZ.pT()/GeV, weight);
 72          _hist_zptpeak_comb_dressed->fill(pZ.pT()/GeV, weight);
 73        }
 74      }
 75
 76      const ZFinder& zfinder_dressed_el_rap = apply<ZFinder>(evt, "ZFinder_dressed_el_rap");
 77      if (!zfinder_dressed_el_rap.bosons().empty()) {
 78        const FourMomentum pZ = zfinder_dressed_el_rap.bosons()[0].momentum();
 79        _hist_zrap_el_dressed->fill(pZ.rapidity()/GeV, weight);
 80        _hist_zrap_comb_dressed->fill(pZ.rapidity()/GeV, weight);
 81      }
 82
 83      const ZFinder& zfinder_dressed_el_pt = apply<ZFinder>(evt, "ZFinder_dressed_el_pt");
 84      if (!zfinder_dressed_el_pt.bosons().empty()) {
 85        const FourMomentum pZ = zfinder_dressed_el_pt.bosons()[0].momentum();
 86        _hist_zpt_el_dressed->fill(pZ.pT()/GeV, weight);
 87        _hist_zpt_comb_dressed->fill(pZ.pT()/GeV, weight);
 88        if (pZ.pT() < 30*GeV) {
 89          _hist_zptpeak_el_dressed->fill(pZ.pT()/GeV, weight);
 90          _hist_zptpeak_comb_dressed->fill(pZ.pT()/GeV, weight);
 91        }
 92      }
 93
 94    }
 95
 96
 97    void finalize() {
 98      normalize(_hist_zrap_mu_dressed);
 99      normalize(_hist_zpt_mu_dressed);
100      normalize(_hist_zptpeak_mu_dressed);
101
102      normalize(_hist_zrap_el_dressed);
103      normalize(_hist_zpt_el_dressed);
104      normalize(_hist_zptpeak_el_dressed);
105
106      normalize(_hist_zrap_comb_dressed);
107      normalize(_hist_zpt_comb_dressed);
108      normalize(_hist_zptpeak_comb_dressed);
109    }
110
111    //@}
112
113
114  private:
115
116    Histo1DPtr _hist_zrap_mu_dressed;
117    Histo1DPtr _hist_zpt_mu_dressed;
118    Histo1DPtr _hist_zptpeak_mu_dressed;
119
120    Histo1DPtr _hist_zrap_el_dressed;
121    Histo1DPtr _hist_zpt_el_dressed;
122    Histo1DPtr _hist_zptpeak_el_dressed;
123
124    Histo1DPtr _hist_zrap_comb_dressed;
125    Histo1DPtr _hist_zpt_comb_dressed;
126    Histo1DPtr _hist_zptpeak_comb_dressed;
127
128  };
129
130
131  RIVET_DECLARE_PLUGIN(CMS_2012_I941555);
132
133}