Rivet analyses

title: ARGUS_1993_I352983

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

Experiment: ARGUS (DORIS)

Inspire ID: 352983

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Lett.B 308 (1993) 435-443

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0

Kinematic distributions in the decay $D^0\to K^0_S\pi^+\pi^-$. Data were read from figure 3 in the paper and the backgrounds given subtracted.

Source code:ARGUS_1993_I352983.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 ARGUS_1993_I352983 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1993_I352983);


/// @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");
  for (unsigned int ix = 0; ix < 3; ++ix) {
    book(_h[ix], 1, 1, 1 + ix);
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // define the decay mode
  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].mom() + K0[0].mom()).mass2();
    double mplus = (pip[0].mom() + K0[0].mom()).mass2();
    double mpipi = (pip[0].mom() + pim[0].mom()).mass2();
    _h[2]->fill(mplus);
    _h[1]->fill(mminus);
    _h[0]->fill(mpipi);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h, 1.0, false);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[3];
const map<PdgId, unsigned int> mode = {{310, 1}, {211, 1}, {-211, 1}};
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_1993_I352983);

} ```