Rivet analyses

title: LHCB_2021_I1915030

Prompt and non-prompt J$/\psi$ production at 5.02 TeV

Experiment: LHCB (LHC)

Inspire ID: 1915030

Status: VALIDATED

Authors: - Peter Richardson

References: - JHEP 11 (2021) 181

Beams: p+ p+

Beam energies: (2510.0, 2510.0)GeV

Run details: - hadronic events with J/psi production

Measurement of the double differential cross section for prompt and non-prompt J$/\psi$ production at 5.02 TeV by the LHCb collaboration.

Source code:LHCB_2021_I1915030.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief J/psi production at 5.02 TeV class LHCB_2021_I1915030 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2021_I1915030);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(), "UFS");
  // histograms
  for (int ix = 0; ix < 3; ++ix) {
    book(_h_JPsi[ix], {2.0, 2.5, 3.0, 3.5, 4.0, 4.5});
    for (int iy = 0; iy < 5; ++iy) {
      if (ix < 2)
        book(_h_JPsi[ix]->bin(iy + 1), ix + 1, 1, iy + 1);
      else
        book(_h_JPsi[ix]->bin(iy + 1), "TMP/JPsi_" + toString(iy), refData(1, 1, iy + 1));
    }
  }
  book(_h_JPsi_pT[0], 3, 1, 1);
  book(_h_JPsi_pT[1], 4, 1, 1);
  book(_h_JPsi_y[0], 5, 1, 1);
  book(_h_JPsi_y[2], 5, 1, 2);
  book(_h_JPsi_y[1], 6, 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");

  for (const Particle& p : ufs.particles(Cuts::pid == 443)) {
    // prompt/non-prompt
    bool nonPrompt = p.fromBottom();
    double absrap = p.absrap();
    double xp = p.perp();
    _h_JPsi[nonPrompt]->fill(absrap, xp);
    _h_JPsi[2]->fill(absrap, xp);
    if (absrap > 2. && absrap < 4.5) _h_JPsi_pT[nonPrompt]->fill(xp);
    if (xp < 14.) _h_JPsi_y[nonPrompt]->fill(absrap);
    if (xp < 8. && !nonPrompt) _h_JPsi_y[2]->fill(absrap);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // factor of 2 due rapidity +/-
  double factor = 0.5 * crossSection() / nanobarn / sumOfWeights();
  for (unsigned int ix = 0; ix < 3; ++ix) {
    scale(_h_JPsi[ix], factor);
    divByGroupWidth(_h_JPsi[ix]);
    scale(_h_JPsi_y[ix], factor);
    if (ix < 2) scale(_h_JPsi_pT[ix], factor);
  }
  for (unsigned int iy = 0; iy < _h_JPsi[0]->numBins(); ++iy) {
    // non-prompt J/psi percentage
    Estimate1DPtr tmp;
    book(tmp, 7, 1, iy + 1);
    efficiency(_h_JPsi[1]->bin(iy + 1), _h_JPsi[2]->bin(iy + 1), tmp);
    tmp->scale(100.);
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DGroupPtr _h_JPsi[3];
Histo1DPtr _h_JPsi_pT[2], _h_JPsi_y[3];
/// @}

};

RIVET_DECLARE_PLUGIN(LHCB_2021_I1915030);

} ```