Rivet analyses

title: JADE_1984_I202785

Spectrum for $D^{*+}$ production in $e^+e^-$ collisions at $E_{\text{CMS}}=34.4$

Experiment: JADE (Petra)

Inspire ID: 202785

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. 104B (1981) 325-329

Beams: e+ e-

Beam energies: (17.2, 17.2)GeV

Run details: - e+ e- to hadrons

Measurement of the $D^{*+}$ momentum spectrum in $e^+e^-$ collisions for a centre-of-mass energy of 34.4 GeV by the JADE experiment at Petra. The angular distribution is also measured.

Source code:JADE_1984_I202785.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief D*+ production at 34.4 GeV class JADE_1984_I202785 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(JADE_1984_I202785);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");

  // Book histograms
  book(_h_x, 1, 1, 1);
  book(_h_theta, 3, 1, 1);
  _axis = YODA::Axis<double>(6, -0.9, 0.9);
}


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

  if (_edges.empty()) _edges = _h_theta->xEdges();
  // Get beams and average beam momentum
  const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
  const double meanBeamMom = (beams.first.p3().mod() + beams.second.p3().mod()) / 2.0;
  MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
  Vector3 axis = beams.first.pid() == PID::EMINUS ? beams.first.p3().unit() : beams.second.p3().unit();
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::abspid == 413)) {
    double modp = p.p3().mod();
    double xE = p.E() / meanBeamMom;
    _h_x->fill(xE);
    if (xE > 0.4 && p.pid() > 0) {
      _h_theta->fill(map2string(p.p3().dot(axis) / modp));
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {

  normalize(_h_theta, 33.6, false); // normalize to data
  scale(_h_x, crossSection() / microbarn / sumOfWeights() * sqr(sqrtS()));
  for (auto& b : _h_theta->bins()) {
    const size_t idx = b.index();
    b.scaleW(1. / _axis.width(idx));
  }
}

/// @}

string map2string(const double value) const {
  const size_t idx = _axis.index(value);
  if (idx && idx <= _edges.size()) return _edges[idx - 1];
  return "OTHER";
}


/// @name Histograms
/// @{
Histo1DPtr _h_x;
BinnedHistoPtr<string> _h_theta;
YODA::Axis<double> _axis;
vector<string> _edges;
/// @}

};

RIVET_DECLARE_PLUGIN(JADE_1984_I202785);

} ```