Rivet analyses

title: E691_1992_I342947

Dalitz plot analysis of $D\to K\pi\pi$ decays

Experiment: E691 (Fermilab)

Inspire ID: 342947

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 48 (1993) 56-62

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0 and D+ mesons

Measurement of the mass distributions in the decays $D^0\to K^-\pi^+\pi^0$, $D^0\to K^0_S\pi^+\pi^-$ and $D^+\to K^-\pi^+\pi^+$. The data were read from the plots in the paper. Resolution/acceptance effects have been not unfolded and no background subtracted therefore given the agreement with the model in the paper this analysis should only be used for qualitative studies.

Source code:E691_1992_I342947.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/DecayedParticles.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief D -> K pi pi dalitz class E691_1992_I342947 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(E691_1992_I342947);


/// @name Analysis methods
/// @{

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  UnstableParticles ufs = UnstableParticles(Cuts::abspid == 411 or Cuts::abspid == 421);
  declare(ufs, "UFS");
  DecayedParticles DD(ufs);
  DD.addStable(PID::PI0);
  DD.addStable(PID::K0S);
  declare(DD, "DD");
  // histograms
  book(_h_1_pipi, 1, 1, 1);
  book(_h_1_Kmpip, 1, 1, 2);
  book(_dalitz1, "dalitz1", 50, 0.3, 3.2, 50, 0.3, 3.2);

  book(_h_2_Kmpip, 1, 1, 3);
  book(_h_2_Kmpi0, 1, 1, 4);
  book(_h_2_pipi, 1, 1, 5);
  book(_dalitz2, "dalitz2", 50, 0.3, 3.2, 50, 0.3, 3.2);

  book(_h_3_K0pip, 1, 1, 7);
  book(_h_3_K0pim, 1, 1, 6);
  book(_h_3_pipi, 1, 1, 8);
  book(_dalitz3, "dalitz3", 50, 0.3, 3.2, 50, 0.3, 3.2);
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  static const map<PdgId, unsigned int>& mode1 = {{211, 1}, {-321, 1}, {111, 1}};
  static const map<PdgId, unsigned int>& mode1CC = {{-211, 1}, {321, 1}, {111, 1}};
  static const map<PdgId, unsigned int>& mode2 = {{211, 1}, {-211, 1}, {310, 1}};
  static const map<PdgId, unsigned int>& mode3 = {{211, 2}, {-321, 1}};
  static const map<PdgId, unsigned int>& mode3CC = {{-211, 2}, {321, 1}};
  // Loop over D+ mesons
  DecayedParticles DD = apply<DecayedParticles>(event, "DD");
  for (unsigned int ix = 0; ix < DD.decaying().size(); ++ix) {
    int sign = DD.decaying()[ix].pid() / DD.decaying()[ix].abspid();
    if (DD.decaying()[ix].abspid() == 421) {
      if ((DD.decaying()[ix].pid() > 0 && DD.modeMatches(ix, 3, mode1))
          || (DD.decaying()[ix].pid() < 0 && DD.modeMatches(ix, 3, mode1CC))) {
        const Particle& pi0 = DD.decayProducts()[ix].at(111)[0];
        const Particle& pip = DD.decayProducts()[ix].at(sign * 211)[0];
        const Particle& Km = DD.decayProducts()[ix].at(-sign * 321)[0];
        double mneut = (Km.momentum() + pip.momentum()).mass2();
        double mminus = (Km.momentum() + pi0.momentum()).mass2();
        double mpipi = (pip.momentum() + pi0.momentum()).mass2();
        _h_2_Kmpip->fill(mneut);
        _h_2_pipi->fill(mpipi);
        _h_2_Kmpi0->fill(mminus);
        _dalitz2->fill(mminus, mneut);
      }
      else if (DD.modeMatches(ix, 3, mode2)) {
        const Particle& K0 = DD.decayProducts()[ix].at(310)[0];
        const Particle& pip = DD.decayProducts()[ix].at(sign * 211)[0];
        const Particle& pim = DD.decayProducts()[ix].at(-sign * 211)[0];
        double mminus = (pim.momentum() + K0.momentum()).mass2();
        double mplus = (pip.momentum() + K0.momentum()).mass2();
        double mpipi = (pip.momentum() + pim.momentum()).mass2();
        _h_3_K0pip->fill(mplus);
        _h_3_K0pim->fill(mminus);
        _h_3_pipi->fill(mpipi);
        _dalitz3->fill(mplus, mminus);
      }
    }
    else if (DD.decaying()[ix].abspid() == 411
             && (DD.modeMatches(ix, 3, mode3) || DD.modeMatches(ix, 3, mode3CC))) {
      const Particles& pip = DD.decayProducts()[ix].at(sign * 211);
      const Particle& Km = DD.decayProducts()[ix].at(-sign * 321)[0];
      double mplus = (Km.momentum() + pip[0].momentum()).mass2();
      double mminus = (Km.momentum() + pip[1].momentum()).mass2();
      double mpipi = (pip[0].momentum() + pip[1].momentum()).mass2();
      _h_1_Kmpip->fill(mminus);
      _h_1_Kmpip->fill(mplus);
      _h_1_pipi->fill(mpipi);
      _dalitz1->fill(mminus, mplus);
      _dalitz1->fill(mplus, mminus);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h_1_pipi);
  normalize(_h_1_Kmpip);
  normalize(_dalitz1);

  normalize(_h_2_Kmpip);
  normalize(_h_2_pipi);
  normalize(_h_2_Kmpi0);
  normalize(_dalitz2);

  normalize(_h_3_K0pip);
  normalize(_h_3_pipi);
  normalize(_h_3_K0pim);
  normalize(_dalitz3);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_1_Kmpip, _h_1_pipi;
Histo2DPtr _dalitz1;
Histo1DPtr _h_2_Kmpip, _h_2_pipi, _h_2_Kmpi0;
Histo2DPtr _dalitz2;
Histo1DPtr _h_3_K0pip, _h_3_pipi, _h_3_K0pim;
Histo2DPtr _dalitz3;
/// @}

};

RIVET_DECLARE_PLUGIN(E691_1992_I342947);

} ```