Rivet analyses

title: ALEPH_1999_I507422

Scaled energy distribution of $D^*$ at LEP

Experiment: ALEPH (LEP)

Inspire ID: 507422

Status: VALIDATED

Authors: - Holger Schulz

References: - Eur.Phys.J.C16:597-611,2000 - hep-ex/9909032 - CERN-EP-99-094

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - Hadronic $Z$ decays at 91.2~GeV.

Study of charm production in $Z$ decays. Here, only the scaled energy distribution of $D^{*\pm}$ is implemented. Should be very important for fragmentation tuning.

Source code:ALEPH_1999_I507422.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

class ALEPH_1999_I507422 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(ALEPH_1999_I507422);


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

  book(_h_Xe_Ds, 1, 1, 1);
}


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

  // Trigger condition
  const ChargedFinalState& cfs = apply<ChargedFinalState>(event, "CFS");
  if (cfs.size() < 5) vetoEvent;

  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

  // 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 / GeV;

  // Accept all D*+- decays.
  for (const Particle& p : select(ufs.particles(), Cuts::abspid == PID::DSTARPLUS)) {
    // Scaled energy.
    const double energy = p.E() / GeV;
    const double scaledEnergy = energy / meanBeamMom;
    _h_Xe_Ds->fill(scaledEnergy);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // brs for D*+/- -> D0 pi+/- and D0->K+pi-
  double br = 0.677 * 0.03950;
  scale(_h_Xe_Ds, 1. / sumOfWeights() * br * 1000.);
}


/// Histogram
Histo1DPtr _h_Xe_Ds;

};

RIVET_DECLARE_ALIASED_PLUGIN(ALEPH_1999_I507422, ALEPH_1999_S4193598);

} ```

Aliases: - ALEPH_1999_S4193598