Rivet analyses

title: LHCB_2014_I1311488

Measurement of the forward $W$ boson cross-section in $pp$ collisions at $\sqrt{s}=7 TeV$

Experiment: LHCB (LHC)

Inspire ID: 1311488

Status: VALIDATED

Authors: - Ilya Segal

References: - LHCB-PAPER-2014-033 - CERN-PH-EP-2014-175 - JHEP 12 (2014) 079 - DOI:10.1007/JHEP12(2014)079 - arXiv: 1408.4354

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - Forward $W$ boson production in $pp$ collisions at $\sqrt{s}=7 TeV$, $p_{T}>20 GeV/c$, $\eta\in[2.0, 4.5]$

A measurement of the inclusive $W \rightarrow \mu\nu$ production cross-section using data from $pp$ collisions at a centre-of-mass energy of $\sqrt{s}=7 TeV$ is presented. Results are reported for muons with a transverse momentum greater than $20 GeV/c$ and pseudorapidity between $2.0$ and $4.5$.

Source code:LHCB_2014_I1311488.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DileptonFinder.hh"

include "Rivet/Projections/LeptonFinder.hh"

namespace Rivet {

/// @brief Forward W boson production in pp collisions at 7 TeV class LHCB_2014_I1311488 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2014_I1311488);


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

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

  // Initialise and register projections
  Cut cuts = (Cuts::pT >= 20.0 * GeV && Cuts::absetaIn(2.0, 4.5) && Cuts::abspid == PID::MUON);
  LeptonFinder wFinder(cuts, 0.0);
  LeptonFinder wFinder_Fsr(cuts, 0.1);
  declare(wFinder, "LeptonFinder");
  declare(wFinder_Fsr, "LeptonFinder_Fsr");

  // Book histograms
  book(_h_wPlusProdEta, 2, 1, 1);
  book(_h_wMinusProdEta, 2, 1, 2);
  book(_h_wPlusProdEta_Fsr, 2, 1, 3);
  book(_h_wMinusProdEta_Fsr, 2, 1, 4);
  book(_h_wRatioEta, 3, 1, 1);
  book(_h_wChargeAsymEta, 4, 1, 1);
  book(_h_wRatioEta_Fsr, 3, 1, 2);
  book(_h_wChargeAsymEta_Fsr, 4, 1, 2);
}


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

  // Searching for W bosons
  const DressedLeptons w = apply<LeptonFinder>(event, "LeptonFinder").dressedLeptons();
  if (w.size() > 0) {
    const Particle& mu = w[0];
    (mu.charge3() > 0 ? _h_wPlusProdEta : _h_wMinusProdEta)->fill(mu.abseta());
  }

  // Searching for W bosons + FSR photon
  const DressedLeptons w_Fsr = apply<LeptonFinder>(event, "LeptonFinder_Fsr").dressedLeptons();
  if (w_Fsr.size() > 0) {
    const Particle& mu = w_Fsr[0];
    (mu.charge3() > 0 ? _h_wPlusProdEta_Fsr : _h_wMinusProdEta_Fsr)->fill(mu.abseta());
  }
}


/// Normalise histograms etc., after the run
void finalize() {

  // Scaling of the histograms and correction on FSR
  const double xs = crossSection() / picobarn;
  const double sf = xs / sumOfWeights() / 2.0;

  scale(_h_wPlusProdEta, sf);
  scale(_h_wPlusProdEta_Fsr, sf);
  scale(_h_wMinusProdEta, sf);
  scale(_h_wMinusProdEta_Fsr, sf);

  //Calculation of ratio and charge asymmetry
  divide(_h_wPlusProdEta, _h_wMinusProdEta, _h_wRatioEta);
  divide(_h_wPlusProdEta_Fsr, _h_wMinusProdEta_Fsr, _h_wRatioEta_Fsr);
  asymm(_h_wPlusProdEta, _h_wMinusProdEta, _h_wChargeAsymEta);
  asymm(_h_wPlusProdEta_Fsr, _h_wPlusProdEta_Fsr, _h_wChargeAsymEta_Fsr);
  scale(_h_wChargeAsymEta, 100);
  scale(_h_wChargeAsymEta_Fsr, 100);
}

///@}


/// @name Histograms
///@{
Histo1DPtr _h_wPlusProdEta;
Histo1DPtr _h_wMinusProdEta;
Histo1DPtr _h_wPlusProdEta_Fsr;
Histo1DPtr _h_wMinusProdEta_Fsr;
Estimate1DPtr _h_wRatioEta;
Estimate1DPtr _h_wChargeAsymEta;
Estimate1DPtr _h_wRatioEta_Fsr;
Estimate1DPtr _h_wChargeAsymEta_Fsr;
///@}

};

RIVET_DECLARE_PLUGIN(LHCB_2014_I1311488);

} ```