Rivet analyses

title: CLEOII_1997_I424575

Spectra for $\Sigma_c^{* ++,0}$ at 10.58 GeV

Experiment: CLEOII (CESR)

Inspire ID: 424575

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 78 (1997) 2304-2308

Beams: e+ e-

Beam energies: (5.3, 5.3)GeV

Run details: - e+e- to hadrons

Spectrum for the average of $\Sigma_c^{0}$ and $\Sigma_c^{++}$ produced at 10.58 GeV measured by CLEOII.

Source code:CLEOII_1997_I424575.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Sigma*_c spectra class CLEOII_1997_I424575 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1997_I424575);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");
  // book histos
  book(_h_cTheta, 2, 1, 1);
  book(_h_x, 3, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // Get beams and average beam momentum
  const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
  const double Emax = (beams.first.p3().mod() + beams.second.p3().mod()) / 2.0;
  const double Pmax = sqrt(sqr(Emax) - sqr(2.518));
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::abspid == 4114 or Cuts::abspid == 4224)) {
    // momentum fraction
    double xp = p.momentum().p3().mod() / Pmax;
    _h_x->fill(xp);
    if (p.children().size() != 2) continue;
    // decay angle
    Particle pi;
    int sign = p.pid() / p.abspid();
    if (p.abspid() == 4224) {
      if (p.children()[0].pid() == sign * 4122 && p.children()[1].pid() == sign * 211) {
        pi = p.children()[1];
      }
      else if (p.children()[1].pid() == sign * 4122 && p.children()[0].pid() == sign * 211) {
        pi = p.children()[0];
      }
      else
        continue;
    }
    else {
      if (p.children()[0].pid() == sign * 4122 && p.children()[1].pid() == -sign * 211) {
        pi = p.children()[1];
      }
      else if (p.children()[1].pid() == sign * 4122 && p.children()[0].pid() == -sign * 211) {
        pi = p.children()[0];
      }
      else
        continue;
    }
    LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
    Vector3 axis = boost.transform(pi.momentum()).p3().unit();
    double cosL = axis.dot(p.momentum().p3().unit());
    _h_cTheta->fill(cosL);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h_x, 1., false);
  normalize(_h_cTheta, 1., false);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_x, _h_cTheta;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEOII_1997_I424575);

} ```