Rivet analyses

title: HRS_1988_I23360

Charm meson spectra in $e^+e^-$ collisions at 29 GeV

Experiment: HRS (PEP)

Inspire ID: 23360

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B206 (1988) 551-556, 1988

Beams: e+ e-

Beam energies: (14.5, 14.5)GeV

Run details: - Hadronic e+e- events at $\sqrt{s} = 29.$ GeV

$D^{*\pm}$, $D^0,\bar{D}^0$ and $D^\pm$ meson momentum spectrum measured at $\sqrt{s} = 29.$ GeV using the HRS detector at PEP. Only the spectra are implemented, not the electroweak asymmetries.

Source code:HRS_1988_I23360.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Charm meson spectra at 29 GeV class HRS_1988_I23360 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(HRS_1988_I23360);


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

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

  // Initialise and register projections
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");
  const ChargedFinalState cfs;
  declare(cfs, "CFS");

  // Book histograms
  book(_h_Dstar1, 1, 1, 1);
  book(_h_Dstar2, 1, 1, 2);
  book(_h_D0, 2, 1, 1);
  book(_h_Dp, 2, 1, 2);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const ChargedFinalState& cfs = apply<ChargedFinalState>(event, "CFS");
  int nch = cfs.particles().size();
  if (nch < 5) vetoEvent;
  // 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);

  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p :
       ufs.particles(Cuts::abspid == 413 || Cuts::abspid == 421 || Cuts::abspid == 411)) {
    double xE = p.E() / meanBeamMom;
    int id = abs(p.pid());
    if (id == 413) {
      _h_Dstar1->fill(xE);
      _h_Dstar2->fill(xE);
    }
    else if (id == 421) {
      _h_D0->fill(xE);
    }
    else if (id == 411) {
      _h_Dp->fill(xE);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  double fact = sqr(sqrtS()) * crossSection() / sumOfWeights() / microbarn;
  scale(_h_Dstar1, fact);
  normalize(_h_Dstar2);
  scale(_h_D0, fact);
  scale(_h_Dp, fact);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_Dstar1, _h_Dstar2, _h_D0, _h_Dp;
/// @}

};

RIVET_DECLARE_PLUGIN(HRS_1988_I23360);

} ```