Rivet analyses

title: ATLAS_2011_I925932

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

Experiment: ATLAS (LHC)

Inspire ID: 925932

Status: VALIDATED

Authors: - Elena Yatsenko - Judith Katzy

References: - Expt page: ATLAS-STDM-2011-15 - arXiv: 1108.6308

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - Run with $W$ decays to $e\,\nu_e$ and/or $\mu\,\nu_\mu$.

The W pT at $\sqrt{s} = 7$~TeV is measured using $W\to e \, \nu_e$ and $W\to \mu \, \nu_\mu$ decay channels. The dressed leptons kinematics calculated from the sum of the post-FSR lepton momentum and the momenta of all photons radiated in a cone around the lepton, while the bare uses the lepton kinematics after all QED radiation.

Source code:ATLAS_2011_I925932.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/LeptonFinder.hh"

include "Rivet/Projections/MissingMomentum.hh"

include "Rivet/Projections/PromptFinalState.hh"

namespace Rivet {

/// ATLAS W pT analysis at 7 TeV class ATLAS_2011_I925932 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2011_I925932);


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

void init() {
  // Set up projections
  Cut cuts = Cuts::abseta < 2.4 && Cuts::pT > 20 * GeV;
  declare("MET", MissingMomentum());
  LeptonFinder ef_dressed(0.2, cuts && Cuts::abspid == PID::ELECTRON);
  declare(ef_dressed, "Elecs_dressed");
  LeptonFinder ef_bare(0.0, cuts && Cuts::abspid == PID::ELECTRON);
  declare(ef_bare, "Elecs_bare");
  LeptonFinder mf_dressed(0.2, cuts && Cuts::abspid == PID::MUON);
  declare(mf_dressed, "Muons_dressed");
  LeptonFinder mf_bare(0.0, cuts && Cuts::abspid == PID::MUON);
  declare(mf_bare, "Muons_bare");

  // Book histograms
  book(_hist_wpt_dressed_el, 1, 1, 2);
  book(_hist_wpt_bare_el, 1, 1, 3);
  book(_hist_wpt_dressed_mu, 2, 1, 2);
  book(_hist_wpt_bare_mu, 2, 1, 3);
}


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

  // W reco, starting with MET
  const P4& pmiss = apply<MissingMom>(event, "MET").missingMom();
  if (pmiss.Et() < 25 * GeV) vetoEvent;

  // Identify the closest-matching l+MET to m == mW
  const Particles& esd = apply<LeptonFinder>(event, "Elecs_dressed").particles();
  const int iedfound = closestMatchIndex(esd, pmiss, Kin::mass, 80.4 * GeV);
  const Particles& esb = apply<LeptonFinder>(event, "Elecs_bare").particles();
  const int iebfound = closestMatchIndex(esb, pmiss, Kin::mass, 80.4 * GeV);
  const Particles& musd = apply<LeptonFinder>(event, "Muons_dressed").particles();
  const int imdfound = closestMatchIndex(musd, pmiss, Kin::mass, 80.4 * GeV);
  const Particles& musb = apply<LeptonFinder>(event, "Muons_bare").particles();
  const int imbfound = closestMatchIndex(musb, pmiss, Kin::mass, 80.4 * GeV);

  MSG_DEBUG("Found " << int(iedfound >= 0) + int(imdfound >= 0) << " dressed W -> e/mu nu");
  MSG_DEBUG("Found " << int(iebfound >= 0) + int(imbfound >= 0) << " bare W -> e/mu nu");
  if (iedfound < 0 && iebfound < 0 && imdfound < 0 && imbfound < 0) {
    MSG_DEBUG("No W bosons found");
    vetoEvent;
  }

  // "Dressed" electron
  if (iedfound >= 0) {
    const Particle& l = esd[iedfound];
    if (mT(pmiss, l) > 40 * GeV) _hist_wpt_dressed_el->fill((l.mom() + pmiss).pT() / GeV);
  }

  // "Bare" electron
  if (iebfound >= 0) {
    const Particle& l = esb[iebfound];
    if (mT(pmiss, l) > 40 * GeV) _hist_wpt_bare_el->fill((l.mom() + pmiss).pT() / GeV);
  }

  // "Dressed" muon
  if (imdfound >= 0) {
    const Particle& l = musd[imdfound];
    if (mT(pmiss, l) > 40 * GeV) _hist_wpt_dressed_mu->fill((l.mom() + pmiss).pT() / GeV);
  }

  // "Bare" muon
  if (imbfound >= 0) {
    const Particle& l = musb[imbfound];
    if (mT(pmiss, l) > 40 * GeV) _hist_wpt_bare_mu->fill((l.mom() + pmiss).pT() / GeV);
  }
}


// Normalize histos
void finalize() {
  normalize(_hist_wpt_dressed_el);
  normalize(_hist_wpt_bare_el);
  normalize(_hist_wpt_dressed_mu);
  normalize(_hist_wpt_bare_mu);
}

/// @}

private:

Histo1DPtr _hist_wpt_dressed_el, _hist_wpt_bare_el, _hist_wpt_dressed_mu, _hist_wpt_bare_mu;

};

RIVET_DECLARE_PLUGIN(ATLAS_2011_I925932);

} ```