Rivet analyses

title: CLEO_2003_I633196

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

Experiment: CLEO (CESR)

Inspire ID: 633196

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 70 (2004) 091101

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0

Kinematic distributions in the decay $D^0\to K^0_S\pi^+\pi^-$

Source code:CLEO_2003_I633196.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 CLEO_2003_I633196 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_2003_I633196);


/// @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_Kpim, 1, 1, 1);
  book(_h_pipi, 1, 1, 2);
  book(_h_Kpip, 1, 1, 3);
  book(_dalitz, "dalitz", 50, 0., 3., 50, 0., 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) {
    if (!D0.modeMatches(ix, 3, mode)) continue;
    int sign = D0.decaying()[ix].pid() / 421;
    const Particles& pip = D0.decayProducts()[ix].at(sign * 211);
    const Particles& pim = D0.decayProducts()[ix].at(-sign * 211);
    const Particles& K0 = D0.decayProducts()[ix].at(310);
    double mminus = (pim[0].momentum() + K0[0].momentum()).mass2();
    double mplus = (pip[0].momentum() + K0[0].momentum()).mass2();
    double mpipi = (pip[0].momentum() + pim[0].momentum()).mass2();
    _h_Kpip->fill(mplus);
    _h_Kpim->fill(mminus);
    _h_pipi->fill(mpipi);
    _dalitz->fill(mminus, mpipi);
  }
}


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

/// @}


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

};

RIVET_DECLARE_PLUGIN(CLEO_2003_I633196);

} ```