Rivet analyses

title: BELLE_2014_I1289224

Dalitz plot analysis of $D^0\to K^0_S\pi^+\pi^-$

Experiment: BELLE (KEKB)

Inspire ID: 1289224

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 89 (2014) 9, 091103

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0

Measurement of Kinematic distributions in the decay $D^0\to K^0_S\pi^+\pi^-$ by BELLE. The data were read from the plots in the paper and for many points the errors are given by the size of the point. Resolution/acceptance effects have been not unfolded.

Source code:BELLE_2014_I1289224.cc

```c++

// -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief D0 -> KS0 pi+ pi- class BELLE_2014_I1289224 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2014_I1289224);


/// @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
  for (unsigned int ix = 0; ix < 3; ++ix) book(_h[ix], 1, 1, 1 + ix);
  book(_dalitz, "dalitz", 50, 0.3, 3.2, 50, 0.3, 3.2);
}


/// Perform the per-event analysis
void analyze(const Event& event) {

  // define the decay mode
  static const map<PdgId, unsigned int>& mode = {{310, 1}, {211, 1}, {-211, 1}};
  DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
  // loop over particles
  for (unsigned int ix = 0; ix < D0.decaying().size(); ++ix) {
    int sign = D0.decaying()[ix].pid() / 421;
    // KS0 pi+pi-
    if (!D0.modeMatches(ix, 3, mode)) continue;
    const Particle& pip = D0.decayProducts()[ix].at(sign * 211)[0];
    const Particle& pim = D0.decayProducts()[ix].at(-sign * 211)[0];
    const Particle& K0 = D0.decayProducts()[ix].at(310)[0];
    double mminus = (pim.momentum() + K0.momentum()).mass2();
    double mplus = (pip.momentum() + K0.momentum()).mass2();
    double mpipi = (pip.momentum() + pim.momentum()).mass2();
    _h[1]->fill(mplus);
    _h[2]->fill(mminus);
    _h[0]->fill(mpipi);
    _dalitz->fill(mminus, mplus);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 0; ix < 3; ++ix) normalize(_h[ix], 1., false);
  normalize(_dalitz);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[3];
Histo2DPtr _dalitz;
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2014_I1289224);

} ```