Rivet analyses

title: CLEO_2000_I526554

$D_s^\pm$ and $D^{*\pm}_s$ spectra in the continuum near the $\Upsilon(4S)$

Experiment: CLEO (CESR)

Inspire ID: 526554

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D62 (2000) 072003, 2000

Beams: e+ e-

Beam energies: (5.3, 5.3)GeV

Run details: - $e^+ e^-$ analysis near the $\Upsilon(4S)$ resonance

Analysis of charm quark fragmentation at 10.5 GeV, based on a data sample of 103 fb collected by the CLEO experiment. Fragmentation into $D^\pm_s$ and $D^{\pm}_s$ mesons is studied. This analysis can be used to constrain charm fragmentation in Monte Carlo generators. The branching ratios $\text{B}_1=B(D^{+}_s\to D_s^+\gamma)B(D_s^+\to\phi\pi^+)B(\phi\to K^+K^-)$ and $B_2=B(D_s^+\to\phi\pi^+)B(\phi\to K^+K^-)$, are not unfolded.

Source code:CLEO_2000_I526554.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Add a short analysis description here class CLEO_2000_I526554 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_2000_I526554);


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

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

  // Book histograms
  book(_h_Ds_star1, 1, 1, 1);
  book(_h_Ds, 2, 1, 1);
  book(_h_Ds_star2, 3, 1, 1);
  book(_h_Ds_primary, 4, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // Loop through unstable FS particles and look for charmed mesons
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

  const Beam beamproj = apply<Beam>(event, "Beams");
  const ParticlePair& beams = beamproj.beams();
  const FourMomentum mom_tot = beams.first.momentum() + beams.second.momentum();
  LorentzTransform cms_boost;
  if (mom_tot.p3().mod() > 1 * MeV)
    cms_boost = LorentzTransform::mkFrameTransformFromBeta(mom_tot.betaVec());
  const double s = sqr(beamproj.sqrtS());
  for (const Particle& p : ufs.particles(Cuts::abspid == 431 or Cuts::abspid == 433)) {
    // 3-momentum in CMS frame
    const double mom = cms_boost.transform(p.momentum()).vector3().mod();
    const int pdgid = p.abspid();
    double mH2(0.), xp(0.);
    bool primary = true;
    switch (pdgid) {
      case 431:
        //   MSG_DEBUG("D_s found");
        mH2 = sqr(1.96834);
        xp = mom / sqrt(s / 4.0 - mH2);
        _h_Ds->fill(xp);
        for (const Particle& mother : p.parents()) {
          if (PID::isCharmMeson(mother.pid())) {
            primary = false;
            break;
          }
        }
        if (primary) _h_Ds_primary->fill(xp);
        break;
      case 433:
        MSG_DEBUG("D_s* found");
        mH2 = sqr(2.1122);
        xp = mom / sqrt(s / 4.0 - mH2);
        _h_Ds_star1->fill(xp);
        _h_Ds_star2->fill(xp);
        break;
      default: break;
    }
  }
}


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

  // BR(D_s->phi pi) x BR(phi->K+K-)
  double br2 = 0.0227;
  // x D_s* -> gamma d_s
  double br1 = br2 * .935;
  // cross section factor
  double fact = crossSection() / picobarn / sumOfWeights();
  // normalize the cross sections (bin width)
  scale(_h_Ds_star1, br1 * fact * 0.03);
  scale(_h_Ds, br2 * fact * 0.03);
  scale(_h_Ds_star2, br2 * fact * 0.03);
  scale(_h_Ds_primary, br2 * fact * 0.03);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_Ds, _h_Ds_primary, _h_Ds_star1, _h_Ds_star2;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEO_2000_I526554);

} ```