Rivet analyses

title: LHCB_2013_I1205646

$J/\psi$ production at 2.76 TeV

Experiment: LHCB (LHC)

Inspire ID: 1205646

Status: VALIDATED

Authors: - Peter Richardson

References: - JHEP 02 (2013) 041, 2013

Beams: p+ p+

Beam energies: (1380.0, 1380.0)GeV

Run details: - J/psi production in pp

Measurement of J/$\psi$ production in the forward region by LHCb at 2.76 TeV.

Source code:LHCB_2013_I1205646.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief J/psi production at 2.76 TeV class LHCB_2013_I1205646 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2013_I1205646);


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

/// Book histograms and initialise projections before the run
void init() {
  // projection
  declare(UnstableParticles(), "UFS");
  // histos
  book(_h_pT, 1, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // Final state of unstable particles to get particle spectra
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  // loop over onium states
  for (const Particle& p : ufs.particles(Cuts::pid == 443)) {
    // cuts on pT and rapidity
    double y = p.absrap();
    double pT = p.perp();
    if (y < 2. || y > 4.5 || pT > 12.) continue;
    _h_pT->fill(pT);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // 0.5 due folded rapidity
  double factor = 0.5 * crossSection() / nanobarn / sumOfWeights();
  scale(_h_pT, factor);
}

///@}


/// @name Histograms
///@{
Histo1DPtr _h_pT;
///@}

};

RIVET_DECLARE_PLUGIN(LHCB_2013_I1205646);

} ```