Rivet analyses

title: CLEOII_1993_I352823

Spectrum for $D^+_{s1}(2536)$ production at 10.58 GeV

Experiment: CLEOII (CESR)

Inspire ID: 352823

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B303 (1993) 377-384

Beams: e+ e-

Beam energies: (5.3, 5.3)GeV

Run details: - e+e- to hadrons

Spectrum for $D^+_{s1}(2536)$ production at 10.58 GeV measured by CLEOII.

Source code:CLEOII_1993_I352823.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Spectrum for D_s1 class CLEOII_1993_I352823 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1993_I352823);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");
  // book histos
  book(_h_x, 3, 1, 1);
  book(_h_cTheta, 4, 1, 1);
  book(_r[0], 2, 1, 1);
  book(_r[1], 2, 1, 2);
}

bool isK0(int id) {
  return id == 310 || id == 130 || abs(id) == 311;
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  static const int DsID = 10433;
  // 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(2.535));
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::abspid == DsID)) {
    // spectrum
    double xp = p.momentum().p3().mod() / Pmax;
    _h_x->fill(xp);
    // decay angle
    int sign = p.pid() / DsID;
    Particle Dstar;
    if (p.children().size() != 2) continue;
    if (p.children()[0].pid() == sign * 423 && p.children()[1].pid() == sign * 321) {
      Dstar = p.children()[0];
    }
    else if (p.children()[1].pid() == sign * 423 && p.children()[0].pid() == sign * 321) {
      Dstar = p.children()[1];
    }
    else if (p.children()[0].pid() == sign * 413 && isK0(p.children()[1].pid())) {
      _r[1]->fill(">= 0.0"s);
      continue;
    }
    else if (p.children()[1].pid() == sign * 413 && isK0(p.children()[0].pid())) {
      _r[1]->fill(">= 0.0"s);
      continue;
    }
    else {
      continue;
    }
    _r[0]->fill(">= 0.0"s);
    if (Dstar.children().size() != 2) continue;
    Particle pion;
    if (Dstar.children()[0].pid() == 111 && Dstar.children()[1].pid() == sign * 421) {
      pion = Dstar.children()[0];
    }
    else if (Dstar.children()[1].pid() == 111 && Dstar.children()[0].pid() == sign * 421) {
      pion = Dstar.children()[1];
    }
    else
      continue;
    // first boost to the D_s1 rest frame
    LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
    FourMomentum pDstar = boost1.transform(Dstar.momentum());
    FourMomentum pPion = boost1.transform(pion.momentum());
    // to D* rest frame
    LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
    Vector3 axis = pDstar.p3().unit();
    FourMomentum pp = boost2.transform(pPion);
    // calculate angle
    double cTheta = pp.p3().unit().dot(axis);
    _h_cTheta->fill(cTheta);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h_x);
  normalize(_h_cTheta);
  scale(_r[0], crossSection() / sumOfWeights() / picobarn);
  scale(_r[1], crossSection() / sumOfWeights() / picobarn);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_x, _h_cTheta;
BinnedHistoPtr<string> _r[2];
/// @}

};

RIVET_DECLARE_PLUGIN(CLEOII_1993_I352823);

} ```