Rivet analyses

Dalitz plot analysis of D0 → K+K−π0

Experiment: BABAR (PEP-II)

Inspire ID: 749390

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 76 (2007) 011102

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0->K+K-pi0, original e+e->Upsilon(4S)

Measurement of the mass distributions in the decay D0 → K+K−π0 by BaBar. The data were read from the plots in the paper. It is also not clear that any resolution effects have been unfolded or backgrounds removed.

Source code:BABAR_2007_I749390.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DecayedParticles.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief D0 -> K+K-pi0
  class BABAR_2007_I749390 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I749390);


    /// @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_Kppi, 1, 1, 1);
      book(_h_Kmpi, 1, 1, 2);
      book(_h_KK, 1, 1, 3);
      book(_dalitz, "dalitz", 50, 0.3, 2.1, 50, 0.3, 2.1);
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{321, 1}, {-321, 1}, {111, 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& pi0 = D0.decayProducts()[ix].at(111);
        const Particles& Kp = D0.decayProducts()[ix].at(sign * 321);
        const Particles& Km = D0.decayProducts()[ix].at(-sign * 321);
        double mplus = (Kp[0].momentum() + pi0[0].momentum()).mass2();
        double mminus = (Km[0].momentum() + pi0[0].momentum()).mass2();
        double mKK = (Kp[0].momentum() + Km[0].momentum()).mass2();
        _h_KK->fill(mKK);
        _h_Kppi->fill(mplus);
        _h_Kmpi->fill(mminus);
        _dalitz->fill(mminus, mplus);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_KK);
      normalize(_h_Kmpi);
      normalize(_h_Kppi);
      normalize(_dalitz);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_KK, _h_Kmpi, _h_Kppi;
    Histo2DPtr _dalitz;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BABAR_2007_I749390);

}