Rivet analyses

Kinematic distributions in the decays D0 → K∓π±π0

Experiment: BABAR (PEP-II)

Inspire ID: 722905

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 97 (2006) 221803

Beams: * *

Beam energies: ANY

Run details: - Any process producing D0

Kinematic distributions in the decays D0 → K∓π±π0. Data read from plots

Source code:BABAR_2006_I722905.cc

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

namespace Rivet {


  /// @brief D0 -> K- pi+ pi0 (or CC)
  class BABAR_2006_I722905 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2006_I722905);


    /// @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 < 2; ++ix) book(_h[ix], 1 + ix, 1, 1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{-321, 1}, {211, 1}, {111, 1}};
      static const map<PdgId, unsigned int>& modeCC = {{321, 1}, {-211, 1}, {111, 1}};
      DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
      // loop over particles
      for (unsigned int ix = 0; ix < D0.decaying().size(); ++ix) {
        int sign = 1;
        if (D0.modeMatches(ix, 3, mode)) {
          sign = 1;
        }
        else if (D0.modeMatches(ix, 3, modeCC)) {
          sign = -1;
        }
        else
          continue;
        const Particle& pi0 = D0.decayProducts()[ix].at(111)[0];
        const Particle& Km = D0.decayProducts()[ix].at(-sign * 321)[0];
        double m2 = (pi0.momentum() + Km.momentum()).mass2();
        if ((D0.decaying()[ix].pid() > 0 && sign == 1) || (D0.decaying()[ix].pid() < 0 && sign == -1))
          _h[0]->fill(m2);
        else
          _h[1]->fill(m2);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 2; ++ix) normalize(_h[ix]);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BABAR_2006_I722905);

}