Rivet analyses

title: ALICE_2012_I1094079

$J/\psi$ production at 2.76 TeV

Experiment: ALICE (LHC)

Inspire ID: 1094079

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett.B 718 (2012) 295-306

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 ALICE at 2.76 TeV. The rate in the central region is also measured, but not the differential cross section.

Source code:ALICE_2012_I1094079.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief J/psi production at 2.76 TeV class ALICE_2012_I1094079 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ALICE_2012_I1094079);


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

/// Book histograms and initialise projections before the run
void init() {
  // projection
  declare(UnstableParticles(Cuts::pid == 443), "UFS");
  // histos
  book(_h_pT, 1, 1, 1);
  book(_h_y, 4, 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 on pT and rapidity
    double y = p.absrap();
    if (y > 2.5 && y < 4.) {
      _h_pT->fill(p.perp());
    }
    _h_y->fill(p.rap());
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  double factor = crossSection() / microbarn / sumOfWeights();
  scale(_h_pT, factor / 3.);
  scale(_h_y, factor);
}

///@}


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

};

RIVET_DECLARE_PLUGIN(ALICE_2012_I1094079);

} ```