Rivet analyses

title: ATLAS_2016_I1409298

Differential cross sections for $J/\psi$ and $\psi(2S)$ at 7 and 8 TeV

Experiment: ATLAS (LHC)

Inspire ID: 1409298

Status: VALIDATED

Authors: - Peter Richardson

References: - Eur.Phys.J.C 76 (2016) 5, 283 - Expt page: ATLAS-BPHY-2012-02 - arXiv: 1512.03657

Beams: p+ p+

Beam energies: (3500.0, 3500.0); (4000.0, 4000.0)GeV

Run details: - hadronic events with J/psi and psi(2S)

Measurement of the double differential (in $p_\perp$ and $y$) cross section for $J/\psi$ and $\psi(2S)$ production at 7 and 8 TeV by the ATLAS collaboration.

Source code:ATLAS_2016_I1409298.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

include "Rivet/Tools/HistoGroup.hh"

namespace Rivet {

/// @brief ATLAS J/psi psi2s at 7 and 8 TeV class ATLAS_2016_I1409298 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ATLAS_2016_I1409298);


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

/// Book histograms and initialise projections before the run
void init() {

  declare(UnstableParticles(Cuts::pid == 443 or Cuts::pid == 100443), "UFS");

  // binning in y
  const vector<double> yedges = {0., 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.};
  // book histos
  size_t ie = 0;
  _ih = 10;
  for (double eVal : allowedEnergies()) {

    if (isCompatibleWithSqrtS(eVal)) _ih = ie;

    for (unsigned int ix = 0; ix < 3; ++ix) {
      book(_h_JPsi[ie][ix], yedges);
      if (ix < 2) book(_h_JPsi[ie][ix + 3], yedges);
      book(_h_psi2S[ie][ix], yedges);
      for (size_t iy = 1; iy < yedges.size(); ++iy) {
        if (ix == 2) {
          // total no for ratios etc
          book(_h_JPsi[ie][ix]->bin(iy), "TMP/JPsi_2_" + toString(iy) + "_" + toString(ie),
               refData(1 + ie, 1, iy));
          book(_h_psi2S[ie][ix]->bin(iy), "TMP/psi2S_2_" + toString(iy) + "_" + toString(ie),
               refData(5 + ie, 1, iy));
          continue;
        }
        // prompt and non-prompt Jpsi
        book(_h_JPsi[ie][ix]->bin(iy), 1 + ie + 2 * ix, 1, iy);
        // prompt and non-prompt psi(2S)
        book(_h_psi2S[ie][ix]->bin(iy), 5 + ie + 2 * ix, 1, iy);
        // extra Jpsi for ratios with psi2s
        if (ix < 2) {
          book(_h_JPsi[ie][ix + 3]->bin(iy),
               "TMP/JPsi_" + toString(ix + 3) + "_" + toString(iy) + "_" + toString(ie),
               refData(5 + ie + 2 * ix, 1, iy));
        }
      }
    }
    ++ie;
  }
  raiseBeamErrorIf(_ih == 10);
}


/// 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()) {
    // prompt/non-prompt
    bool nonPrompt = p.fromBottom();
    const double absrap = p.absrap();
    const double xp = p.perp();
    if (p.pid() == 443) {
      _h_JPsi[_ih][nonPrompt]->fill(absrap, xp);
      _h_JPsi[_ih][2]->fill(absrap, xp);
      _h_JPsi[_ih][nonPrompt + 3]->fill(absrap, xp);
    }
    else {
      _h_psi2S[_ih][nonPrompt]->fill(absrap, xp);
      _h_psi2S[_ih][2]->fill(absrap, xp);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // 1/2 due rapidity folding +/-
  const double factor = 0.5 * crossSection() / nanobarn / sumOfWeights();
  // br to muons PDG 2021 (psi2s is e+e- due large errors on mu+mu-)
  const vector<double> br = {0.05961, 0.00793};
  for (size_t ie = 0; ie < 2; ++ie) {
    // scale histos
    for (size_t ix = 0; ix < 5; ++ix) {
      scale(_h_JPsi[ie][ix], factor * br[0]);
      divByGroupWidth(_h_JPsi[ie][ix]);
      if (ix > 2) continue;
      scale(_h_psi2S[ie][ix], factor * br[1]);
      divByGroupWidth(_h_psi2S[ie][ix]);
    }
    // ratios
    for (size_t iy = 1; iy <= _h_JPsi[ie][0]->numBins(); ++iy) {
      // non-prompt J/psi percentage
      Estimate1DPtr tmp;
      book(tmp, 9 + ie, 1, iy);
      efficiency(_h_JPsi[ie][1]->bin(iy), _h_JPsi[ie][2]->bin(iy), tmp);
      tmp->scale(100.);
      // non-prompt psi2S percentage
      book(tmp, 11 + ie, 1, iy);
      efficiency(_h_psi2S[ie][1]->bin(iy), _h_psi2S[ie][2]->bin(iy), tmp);
      tmp->scale(100.);
      // prompt psi(2s)/J/psi percentage
      book(tmp, 13 + ie, 1, iy);
      divide(_h_psi2S[ie][0]->bin(iy), _h_JPsi[ie][3]->bin(iy), tmp);
      tmp->scale(100.);
      // non-prompt psi(2s)/J/psi percentage
      book(tmp, 15 + ie, 1, iy);
      divide(_h_psi2S[ie][1]->bin(iy), _h_JPsi[ie][4]->bin(iy), tmp);
      tmp->scale(100.);
    }
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DGroupPtr _h_JPsi[2][5], _h_psi2S[2][3];
size_t _ih;
/// @}

};

RIVET_DECLARE_PLUGIN(ATLAS_2016_I1409298);

} ```