Rivet analyses

title: LHCB_2015_I1391511

J/$\psi$ production at 13 TeV

Experiment: LHCB (LHC)

Inspire ID: 1391511

Status: VALIDATED

Authors: - Peter Richardson

References: - JHEP 10 (2015) 172, 2015.

Beams: p+ p+

Beam energies: (6500.0, 6500.0)GeV

Run details: - J/psi production

Measurement of the double differential (in $p_\perp$ and $y$) cross section for $J/\psi$ production at 13 TeV by the LHCB collaboration.

Source code:LHCB_2015_I1391511.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief J/psi production at 13 TeV class LHCB_2015_I1391511 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2015_I1391511);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(), "UFS");
  for (unsigned int ix = 0; ix < 3; ++ix) {
    book(_h_Jpsi[ix], {2.0, 2.5, 3.0, 3.5, 4.0, 4.5});
    for (unsigned int iy = 0; iy < 5; ++iy) {
      if (ix < 2)
        book(_h_Jpsi[ix]->bin(iy + 1), 1 + ix, 1, iy + 1);
      else
        book(_h_Jpsi[ix]->bin(iy + 1), "TMP/Jpsi_" + toString(iy), refData(3, 1, iy + 1));
    }
  }
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h_pT[ix], 4 + ix, 1, 1);
    book(_h_y[ix], 6 + ix, 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");
  // J/psi
  for (const Particle& p : ufs.particles(Cuts::pid == 443)) {
    // prompt/non-prompt
    bool nonPrompt = p.fromBottom();
    double absrap = p.absrap();
    double xp = p.perp();
    if (absrap < 2. || absrap > 4.5 || xp > 14.) continue;
    _h_Jpsi[nonPrompt]->fill(absrap, xp);
    _h_Jpsi[2]->fill(absrap, xp);
    _h_pT[nonPrompt]->fill(xp);
    _h_y[nonPrompt]->fill(absrap);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // 1/2 due rapidity folding +/-
  double factor = 0.5 * crossSection() / nanobarn / sumOfWeights();
  for (unsigned int ix = 0; ix < 3; ++ix) {
    scale(_h_Jpsi[ix], factor);
    divByGroupWidth(_h_Jpsi[ix]);
  }
  Estimate1DPtr tmp;
  for (unsigned int ix = 0; ix < _h_Jpsi[1]->numBins(); ++ix) {
    book(tmp, 3, 1, 1 + ix);
    divide(_h_Jpsi[1]->bin(ix + 1), _h_Jpsi[2]->bin(ix + 1), tmp);
    tmp->scale(100.);
  }
  for (unsigned int ix = 0; ix < 2; ++ix) {
    scale(_h_pT[ix], factor);
    scale(_h_y[ix], factor * 1e-3);
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DGroupPtr _h_Jpsi[3];
Histo1DPtr _h_pT[2], _h_y[2];
/// @}

};

RIVET_DECLARE_PLUGIN(LHCB_2015_I1391511);

} ```