Rivet analyses

title: CLEOC_2011_I913909

Dalitz plot analysis of $D^0\to K_S^0\pi^0\pi^0$

Experiment: CLEOC (CESR)

Inspire ID: 913909

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 84 (2011) 092005

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0 -> KS0 pi0 pi0

Measurement of the mass distributions in the decay $D^0\to K_S^0\pi^0\pi^0$. The data were read from the plots in the paper, with the background given subtracted. Resolution/acceptance effects have been not unfolded and given the agreement with the model in the paper this analysis should only be used for qualitative studies.

Source code:CLEOC_2011_I913909.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief D0 -> K0 pi0pi0 class CLEOC_2011_I913909 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEOC_2011_I913909);


/// @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_pipi, 1, 1, 2);
  book(_dalitz, "dalitz", 50, 0., 1.9, 50, 0.3, 3.1);
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode = {{111, 2}, {310, 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& K0 = D0.decayProducts()[ix].at(310);
    const Particles& pi0 = D0.decayProducts()[ix].at(111);
    double mpipi = (pi0[0].momentum() + pi0[1].momentum()).mass2();
    _h_pipi->fill(mpipi);
    for (unsigned int ix = 0; ix < 2; ++ix) {
      double mKpi = (K0[0].momentum() + pi0[ix].momentum()).mass2();
      _h_Kpi->fill(mKpi);
      _dalitz->fill(mpipi, mKpi);
    }
  }
}


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

/// @}


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

};

RIVET_DECLARE_PLUGIN(CLEOC_2011_I913909);

} ```