Rivet analyses

title: LHCB_2020_I1763898

Prompt and non-prompt $\eta_c$ production at 13 TeV

Experiment: LHCB (LHC)

Inspire ID: 1763898

Status: VALIDATED

Authors: - Peter Richardson

References: - Eur.Phys.J.C 80 (2020) 3, 191

Beams: p+ p+

Beam energies: (6500.0, 6500.0)GeV

Run details: - hadronic events with eta_c and J/psi production

Measurement of the differential cross section with respect to $p_\perp$ of $\eta_c$ production at 13 TeV by the LHCb collaboration.

Source code:LHCB_2020_I1763898.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief eta_c production at 13 TeV class LHCB_2020_I1763898 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2020_I1763898);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(), "UFS");
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h_etac[ix], 2 + 2 * ix, 1, 1);
    book(_h_Jpsi[ix], "TMP/Jpsi" + toString(ix), refData(2 + 2 * 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");

  for (const Particle& p : ufs.particles(Cuts::pid == 441 || Cuts::pid == 443)) {
    // prompt/non-prompt
    bool nonPrompt = p.fromBottom();
    double absrap = p.absrap();
    double xp = p.perp();
    if (absrap > 2. && absrap < 4.5) {
      if (p.pid() == 441)
        _h_etac[nonPrompt]->fill(xp);
      else
        _h_Jpsi[nonPrompt]->fill(xp);
    }
  }
}


/// 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 < 2; ++ix) {
    scale(_h_etac[ix], factor);
    scale(_h_Jpsi[ix], factor);
    Estimate1DPtr tmp;
    book(tmp, 1 + 2 * ix, 1, 1);
    divide(_h_etac[ix], _h_Jpsi[ix], tmp);
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_etac[2], _h_Jpsi[2];
/// @}

};

RIVET_DECLARE_PLUGIN(LHCB_2020_I1763898);

} ```