Rivet analyses

title: CMS_2016_I1471281

Measurement of the transverse momentum spectra of weak vector bosons produced in proton-proton collisions at $\sqrt{s} = 8$ TeV

Experiment: CMS (LHC)

Inspire ID: 1471281

Status: VALIDATED

Authors: - SangEun Lee d4space@google.com - Khakimjan Butanov khakimjan@yahoo.com - Hammid Yusupov hamid_yusupov@yahoo.com - SangIl Pak spak@cern.ch

References: - JHEP 02(2016)096 - DOI:10.1007/JHEP02(2017)096 - arXiv: 1606.05864

Beams: p+ p+

Beam energies: (4000.0, 4000.0)GeV

Run details: - Run MC generators with $W$ and $Z$ bosons decaying to muons in $pp$ collisions at $sqrt{s} = 8$ TeV.

A measurement of the $W$ and $Z$ bosons production differential cross section as a function of transverse momentum of weak vector bosons in $pp$ collisions at a centre-of-mass energy of 8 TeV. Both $W$ and $Z$ distributions are pre-FSR level and events are generated by Powheg. For the $Z$ boson analysis, the dimuon invariant mass selection, $60 < m < 120$ GeV.

Source code:CMS_2016_I1471281.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DileptonFinder.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/LeptonFinder.hh"

include "Rivet/Projections/MissingMomentum.hh"

include "Rivet/Projections/PromptFinalState.hh"

namespace Rivet {

/// Measurement of the W and Z bosons pT produced in pp collisions at sqrt(s)=8 TeV class CMS_2016_I1471281 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2016_I1471281)


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

/// Book histograms and initialise projections before the run
void init() {

  // Get options from the new option system
  // default to both.
  if (getOption("VMODE") == "BOTH") _mode = 0;
  if (getOption("VMODE") == "W") _mode = 1;
  if (getOption("VMODE") == "Z") _mode = 2;

  // Set up projections
  Cut cut_mu = Cuts::abseta < 2.1 && Cuts::pT > 20 * GeV;

  // Dressed W's
  PromptFinalState mufs(cut_mu && Cuts::abspid == PID::MUON);
  declare(mufs, "Muons");
  declare(MissingMomentum(), "MET");

  // Dressed Z's
  /// @note There's no protection in this analysis to ensure the Z and W don't use the same muon
  DileptonFinder zmumu_Finder(91.2 * GeV, 0.0, cut_mu && Cuts::abspid == PID::MUON,
                              Cuts::massIn(60 * GeV, 120 * GeV)); //< no dressing
  declare(zmumu_Finder, "Zmumu_Finder");

  // Histograms
  if (_mode == 0 || _mode == 1) {
    book(_hist_WtoMuNuPt, 8, 1, 1);
  }
  if (_mode == 0 || _mode == 2) {
    book(_hist_ZtoMuMuPt, 9, 1, 1);
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {

  if (_mode == 0 || _mode == 1) {
    // Get the W bosons - muon decay channel
    const P4& pmiss = apply<MissingMomentum>(event, "MET").missingMom();
    const Particles& mus = apply<PromptFinalState>(event, "Muons").particles();
    const Particles mus_mtfilt = select(mus, [&](const Particle& m) { return mT(m, pmiss) > 0 * GeV; });
    const int imfound = closestMatchIndex(mus_mtfilt, pmiss, Kin::mass, 80.4 * GeV);
    if (imfound >= 0) {
      const FourMomentum pWmunu = mus_mtfilt[imfound] + pmiss;
      _hist_WtoMuNuPt->fill(pWmunu.pT() / GeV);
    }
  }

  if (_mode == 0 || _mode == 2) {
    // Get the Z bosons - muon decay channel
    /// @todo Note overlap with the W muon in diboson events
    const DileptonFinder& zmumu_Finder = apply<DileptonFinder>(event, "Zmumu_Finder");
    if (!zmumu_Finder.bosons().empty()) {
      const FourMomentum pZmumu = zmumu_Finder.bosons()[0].momentum();
      _hist_ZtoMuMuPt->fill(pZmumu.pT() / GeV);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  MSG_DEBUG("Cross section = " << std::setfill(' ') << std::setw(14) << std::fixed << std::setprecision(3)
                               << crossSection() / picobarn << " pb");
  MSG_DEBUG("# Events      = " << std::setfill(' ') << std::setw(14) << std::fixed << std::setprecision(3)
                               << numEvents());
  MSG_DEBUG("SumW          = " << std::setfill(' ') << std::setw(14) << std::fixed << std::setprecision(3)
                               << sumOfWeights());
  if (_mode == 0 || _mode == 1) normalize(_hist_WtoMuNuPt);
  if (_mode == 0 || _mode == 2) normalize(_hist_ZtoMuMuPt);
}

/// @}

private:

// Data members
size_t _mode = 0;


/// @name Histograms
/// @{
Histo1DPtr _hist_WtoMuNuPt;
Histo1DPtr _hist_ZtoMuMuPt;
/// @}

};

RIVET_DECLARE_PLUGIN(CMS_2016_I1471281);

} ```