Rivet analyses

title: ALICE_2019_I1735351

Central J$/\psi$ production at $5.02$ TeV

Experiment: ALICE (LHC)

Inspire ID: 1735351

Status: VALIDATED

Authors: - Peter Richardson

References: - JHEP 10 (2019) 084

Beams: p+ p+

Beam energies: (2510.0, 2510.0)GeV

Run details: - J/Psi production

Measurement of central J$/\psi$ production at $5.02$ TeV by the ALICE collaboration.

Source code:ALICE_2019_I1735351.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief J/psi at 5.02 TeV class ALICE_2019_I1735351 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ALICE_2019_I1735351);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(Cuts::pid == 443), "UFS");
  book(_h_JPsi_pT, 2, 1, 1);
  _axis = YODA::Axis<double>({0., 1., 2., 3., 4., 5., 7., 10.});
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  if (_edges.empty()) _edges = _h_JPsi_pT->xEdges();
  // loop over J/Psi
  for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
    // rapidity cut
    if (p.absrap() > 0.9) continue;
    _h_JPsi_pT->fill(discEdge(p.perp()));
  }
}

string discEdge(double val) const {
  string edge("OTHER");
  size_t idx = _axis.index(val);
  if (0 < idx && idx <= _axis.numBins()) return _edges[idx - 1];
  return edge;
}


/// Normalise histograms etc., after the run
void finalize() {
  // factor 1/2 due folding +/- rap and 1.8 due y range
  double fact = 0.5 / 1.8 * crossSection() / nanobarn / sumOfWeights();
  scale(_h_JPsi_pT, fact);
  for (auto& b : _h_JPsi_pT->bins()) {
    b.scaleW(1. / _axis.width(b.index()));
  }
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _h_JPsi_pT;
YODA::Axis<double> _axis;
vector<string> _edges;
/// @}

};

RIVET_DECLARE_PLUGIN(ALICE_2019_I1735351);

} ```