Rivet analyses

title: CLEO_2004_I649917

Dalitz decay of $D^0\to K^0_S\pi^0\eta$

Experiment: CLEO (CESR)

Inspire ID: 649917

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 93 (2004) 111801

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0 mesons

Measurement of the mass distributions in the decay $D^0\to K^0_S\pi^0\eta$ by CLEO. The data were read from the plots in the paper. It is also not clear that any resolution effects have been unfolded.

Source code:CLEO_2004_I649917.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief D0 -> KS0 pi0 eta class CLEO_2004_I649917 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_2004_I649917);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 421);
  declare(ufs, "UFS");
  DecayedParticles D0(ufs);
  D0.addStable(PID::PI0);
  D0.addStable(PID::K0S);
  D0.addStable(PID::ETA);
  D0.addStable(PID::ETAPRIME);
  declare(D0, "D0");
  // histograms
  book(_h_Kpi, 1, 1, 1);
  book(_h_etapi, 1, 1, 2);
  book(_h_Keta, 1, 1, 3);
  book(_dalitz, "dalitz", 50, 0.4, 1.9, 50, 0.3, 1.8);
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  // define the decay mode
  static const map<PdgId, unsigned int>& mode = {{310, 1}, {221, 1}, {111, 1}};
  DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
  // loop over particles
  for (unsigned int ix = 0; ix < D0.decaying().size(); ++ix) {
    if (!D0.modeMatches(ix, 3, mode)) continue;
    const Particles& pi0 = D0.decayProducts()[ix].at(111);
    const Particles& eta = D0.decayProducts()[ix].at(221);
    const Particles& K0 = D0.decayProducts()[ix].at(310);
    double metapi = (eta[0].momentum() + pi0[0].momentum()).mass2();
    double metaK = (eta[0].momentum() + K0[0].momentum()).mass2();
    double mKpi = (K0[0].momentum() + pi0[0].momentum()).mass2();
    _dalitz->fill(metapi, mKpi);
    _h_etapi->fill(metapi);
    _h_Keta->fill(metaK);
    _h_Kpi->fill(mKpi);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h_Kpi);
  normalize(_h_etapi);
  normalize(_h_Keta);
  normalize(_dalitz);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_Kpi, _h_etapi, _h_Keta;
Histo2DPtr _dalitz;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEO_2004_I649917);

} ```