Rivet analyses

Dalitz decay of D0 → KS0π0η

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 D0 → KS0π0η 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++ -*-
#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);

}