Rivet analyses

title: CDF_1997_I440101

$J/\psi$ and $\psi(2S)$ production at 1.8 TeV

Experiment: CDF (Tevatron)

Inspire ID: 440101

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 79 (1997) 572-577

Beams: p- p+

Beam energies: (900.0, 900.0)GeV

Run details: - J/psi and psi(2S) production

Measurement of the differential cross section with respect to $p_\perp$ for $J/\psi$ and $\psi(2S)$ production at 1.8 TeV by the CDF collaboration.

Source code:CDF_1997_I440101.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief J/psi and psi(2S) at 1.8 TeV class CDF_1997_I440101 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CDF_1997_I440101);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(), "UFS");
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h_total[ix], 1, 1, 1 + ix);
    for (unsigned int iy = 0; iy < 2; ++iy) {
      book(_h_psi[ix][iy], 2 + 2 * ix + iy, 1, 1);
    }
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {

  if (_edges.empty()) {
    _edges.resize(2);
    for (unsigned int ix = 0; ix < 2; ++ix) {
      _edges[ix].resize(2);
      for (unsigned int iy = 0; iy < 2; ++iy) _edges[ix][iy] = _h_psi[ix][iy]->xEdges();
    }
  }

  // Final state of unstable particles to get particle spectra
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

  for (const Particle& p : ufs.particles(Cuts::pid == 443 or Cuts::pid == 100443)) {
    const double abseta = p.abseta();
    const double xp = p.perp();
    if (xp < 5. || abseta > 0.6) continue;
    bool prompt = !p.fromBottom();
    unsigned int ipsi = p.pid() / 100000;
    _h_total[ipsi]->fill("< 0.6"s);
    _h_psi[prompt][ipsi]->fill(disc(xp, prompt, ipsi));
  }
}

string disc(const double value, unsigned int prompt, unsigned int ipsi) const {
  size_t idx = _axis[ipsi].index(value);
  if (0 < idx && idx <= _axis[ipsi].numBins()) return _edges[prompt][ipsi][idx - 1];
  return "OTHER"s;
}


/// Normalise histograms etc., after the run
void finalize() {
  // normalisation factor
  const double factor = 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 (unsigned int ix = 0; ix < 2; ++ix) {
    scale(_h_total[ix], factor * br[ix]);
    for (unsigned int iy = 0; iy < 2; ++iy) {
      scale(_h_psi[ix][iy], factor * br[iy]);
      for (auto& b : _h_psi[ix][iy]->bins()) {
        b.scaleW(1. / _axis[iy].width(b.index()));
      }
    }
  }
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _h_total[2], _h_psi[2][2];
YODA::Axis<double> _axis[2] = {YODA::Axis<double>(
                                   {5., 5.5, 6., 6.5, 7., 8., 9., 10., 12., 14., 17., 20.}),
                               YODA::Axis<double>({5., 6., 7., 9., 12., 16.})};
vector<vector<vector<string>>> _edges;
/// @}

};

RIVET_DECLARE_PLUGIN(CDF_1997_I440101);

} ```