Rivet analyses

Differential cross sections for J/ψ production at 7 TeV

Experiment: LHCB (LHC)

Inspire ID: 891233

Status: VALIDATED

Authors: - Peter Richardson

References: - Eur.Phys.J.C 71 (2011) 1645

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - hadronic events with Jpsi production

Measurement of the double differential (in p_⟂ and y) cross section for J/ψ production at 7 TeV by the LHCB collaboration.

Source code:`LHCB_2011_I891233.cc`

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief J/psi production at 7 TeV
  class LHCB_2011_I891233 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2011_I891233);


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

    /// Book histograms and initialise projections before the run
    void init() {
      declare(UnstableParticles(), "UFS");
      for (unsigned int ix = 0; ix < 5; ++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 < 4)
            book(_h_Jpsi[ix]->bin(iy + 1), 6 + ix, 1, iy + 1);
          else
            book(_h_Jpsi[ix]->bin(iy + 1), "TMP/JPsi_" + toString(iy), refData(6, 1, iy + 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[4]->fill(absrap, xp);
        if (nonPrompt) {
          _h_Jpsi[1]->fill(absrap, xp);
        }
        else {
          _h_Jpsi[0]->fill(absrap, xp);
          _h_Jpsi[2]->fill(absrap, xp);
          _h_Jpsi[3]->fill(absrap, 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 < 5; ++ix) {
        scale(_h_Jpsi[ix], factor);
        divByGroupWidth(_h_Jpsi[ix]);
      }
      for (unsigned int ix = 0; ix < _h_Jpsi[4]->numBins(); ++ix) {
        Estimate1DPtr tmp;
        book(tmp, 10, 1, ix + 1);
        divide(_h_Jpsi[1]->bin(ix + 1), _h_Jpsi[4]->bin(ix + 1), tmp);
        tmp->scale(100.);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DGroupPtr _h_Jpsi[5];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(LHCB_2011_I891233);

}

Rivet analyses

Differential cross sections for J/ψ production at 7 TeV

Source code:LHCB_2011_I891233.cc

Source code:`LHCB_2011_I891233.cc`