Rivet analyses

Prompt J/ψ and ψ(2S) production at 7 TeV

Experiment: CMS (LHC)

Inspire ID: 1345023

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 114 (2015) 191802, 2015. - Expt page: CMS-BPH-14-001 - arXiv: 1502.04155

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - J/psi and psi(2s) production in pp

Measurement of prompt J/ψ and ψ(2S) at 7 TeV by the CMS collaboration. The transverse momentum spectra are measured in a numbver of rapidity intervals, together with the ratio of the production of the ψ(2S) to the J/ψ.

Source code:`CMS_2015_I1345023.cc`

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


namespace Rivet {


  /// @brief prompt J/psi and psi(2S) at 7 TeV
  class CMS_2015_I1345023 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2015_I1345023);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projection
      declare(UnstableParticles(), "UFS");
      // J/psi/psi(2s) histos
      for (unsigned int ipsi = 0; ipsi < 2; ++ipsi) {
        book(_h_psi[ipsi], {0., 0.3, 0.6, 0.9, 1.2});
        for (unsigned int iy = 1; iy < 5; ++iy) {
          Histo1DPtr tmp;
          book(_h_psi[ipsi]->bin(iy), ipsi + 1, 1, iy);
        }
        book(_h_pT[ipsi][0], 3 + ipsi, 1, 1);
        book(_h_pT[ipsi][1], "TMP/psi_" + toString(ipsi), refData(5, 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");
      // loop over onium states
      for (const Particle& p : ufs.particles(Cuts::pid == 443 or Cuts::pid == 100443)) {
        // prompt
        if (p.fromBottom()) continue;
        // cuts on rapidity
        const double y = p.absrap();
        if (y > 1.2) continue;
        const double pT = p.perp();
        unsigned int ipsi = p.pid() / 100000;
        _h_psi[ipsi]->fill(y, pT);
        _h_pT[ipsi][0]->fill(pT);
        _h_pT[ipsi][1]->fill(pT);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // 0.5 due folded rapidity
      const double factor = 0.5 * crossSection() / picobarn / sumOfWeights();
      // branching ratios to muons
      const vector<double> brs = {0.05961, 0.00793};
      for (unsigned int ix = 0; ix < 2; ++ix) {
        scale(_h_psi[ix], factor * brs[ix]);
        divByGroupWidth(_h_psi[ix]);
        scale(_h_pT[ix][0], brs[ix] * factor / 1.2);
        scale(_h_pT[ix][1], brs[ix] * factor / 1.2);
      }
      // ratio plots
      Estimate1DPtr tmp;
      book(tmp, 5, 1, 1);
      divide(_h_pT[1][1], _h_pT[0][1], tmp);
      // convert to %age
      tmp->scale(100.);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DGroupPtr _h_psi[2];
    Histo1DPtr _h_pT[2][2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CMS_2015_I1345023);

}

Rivet analyses

Prompt J/ψ and ψ(2S) production at 7 TeV

Source code:CMS_2015_I1345023.cc

Source code:`CMS_2015_I1345023.cc`