Rivet analyses

title: CMS_2015_I1345023

Prompt J/$\psi$ and $\psi(2S)$ 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 $J/\psi$ and $\psi(2S)$ 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 $\psi(2S)$ to the $J/\psi$.

Source code:CMS_2015_I1345023.cc

```c++ // -- 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);

} ```