Rivet analyses

J/ψ 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_⟂ and y) cross section for J/ψ production at 13 TeV by the LHCB collaboration.

Source code:`LHCB_2015_I1391511.cc`

// -*- 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);

}

Rivet analyses

J/ψ production at 13 TeV

Source code:LHCB_2015_I1391511.cc

Source code:`LHCB_2015_I1391511.cc`