Rivet analyses

Prompt and non-prompt ηc 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⟂ of ηc production at 13 TeV by the LHCb collaboration.

Source code:LHCB_2020_I1763898.cc

// -*- 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);

}