Rivet analyses

Mass distributions in the decays D0 → K−π+ω, D0 → KS0π0ω, D+ → KS0π+ω

Experiment: BESIII (BEPC)

Inspire ID: 1940222

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 105 (2022) 3, 032009

Beams: * *

Beam energies: ANY

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

Measurement of the mass distributions in the decays D0 → K−π+ω, D0 → KS0π0ω, D+ → KS0π+ω by BES. The data were read from the plots in the paper and therefore for some points the error bars are the size of the point. It is also not clear that any resolution effects have been unfolded.

Source code:BESIII_2021_I1940222.cc

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

namespace Rivet {


  /// @brief D -> omega decays
  class BESIII_2021_I1940222 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1940222);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid==411||
                        Cuts::abspid==421);
      declare(ufs, "UFS");
      DecayedParticles DD(ufs);
      DD.addStable(PID::PI0);
      DD.addStable(PID::K0S);
      DD.addStable(PID::ETA);
      DD.addStable(PID::ETAPRIME);
      DD.addStable(PID::OMEGA);
      declare(DD, "DD");
      // histograms
      for(unsigned int ix=0;ix<9;++ix)
    book(_h[ix],1,1,1+ix);
      for(unsigned int ix=0;ix<3;++ix)
    book(_dalitz[ix],"dalitz_"+toString(ix+1),50,0.4,1.2,50,0.8,1.9);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // define the decay modes
      static const map<PdgId,unsigned int> & mode1   = { {-321,1},{ 211,1}, { 223,1}};
      static const map<PdgId,unsigned int> & mode1CC = { { 321,1},{-211,1}, { 223,1}};
      static const map<PdgId,unsigned int> & mode2   = { { 310,1},{ 111,1}, { 223,1}};
      static const map<PdgId,unsigned int> & mode3   = { { 310,1},{ 211,1}, { 223,1}};
      static const map<PdgId,unsigned int> & mode3CC = { { 310,1},{-211,1}, { 223,1}};
      DecayedParticles DD = apply<DecayedParticles>(event, "DD");
      // loop over particles
      for(unsigned int ix=0;ix<DD.decaying().size();++ix) {
    // D0 -> K- pi+ omega
    if( (DD.decaying()[ix].pid()== 421 && DD.modeMatches(ix,3,mode1)) ||
        (DD.decaying()[ix].pid()==-421 && DD.modeMatches(ix,3,mode1CC))) {
      int sign = DD.decaying()[ix].pid()/421;
      const Particles & pip   = DD.decayProducts()[ix].at( sign*211);
      const Particles & Km    = DD.decayProducts()[ix].at(-sign*321);
      const Particles & omega = DD.decayProducts()[ix].at(223);
      double mKpi     = (pip[0].momentum()+Km[0].momentum()).mass2();
      double mpiomega = (pip[0].momentum()+omega[0].momentum()).mass2();
      _dalitz[0]->fill(mKpi,mpiomega);
      _h[0]->fill(sqrt(mKpi));
      _h[1]->fill((Km[0].momentum()+omega[0].momentum()).mass());
      _h[2]->fill(sqrt(mpiomega));
      
    }
    // D0 -> KS0 pi0 omega
    else if (DD.decaying()[ix].abspid()==421 && DD.modeMatches(ix,3,mode2)) {
      const Particles & pi0   = DD.decayProducts()[ix].at(111);
      const Particles & KS0   = DD.decayProducts()[ix].at(310);
      const Particles & omega = DD.decayProducts()[ix].at(223);
      double mKpi     = (pi0[0].momentum()+KS0[0].momentum()).mass2();
      double mpiomega = (pi0[0].momentum()+omega[0].momentum()).mass2();
      _dalitz[1]->fill(mKpi,mpiomega);
      _h[3]->fill(sqrt(mKpi));
      _h[4]->fill((KS0[0].momentum()+omega[0].momentum()).mass());
      _h[5]->fill(sqrt(mpiomega));
    }
    // D0 -> K- pi+ omega
    else if( (DD.decaying()[ix].pid()== 411 && DD.modeMatches(ix,3,mode3)) ||
         (DD.decaying()[ix].pid()==-411 && DD.modeMatches(ix,3,mode3CC))) {
      int sign = DD.decaying()[ix].pid()/411;
      const Particles & pip   = DD.decayProducts()[ix].at( sign*211);
      const Particles & KS0   = DD.decayProducts()[ix].at(310);
      const Particles & omega = DD.decayProducts()[ix].at(223);
      double mKpi     = (pip[0].momentum()+KS0[0].momentum()).mass2();
      double mpiomega = (pip[0].momentum()+omega[0].momentum()).mass2();
      _dalitz[2]->fill(mKpi,mpiomega);
      _h[6]->fill(sqrt(mKpi));
      _h[7]->fill((KS0[0].momentum()+omega[0].momentum()).mass());
      _h[8]->fill(sqrt(mpiomega));
      
    }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for(unsigned int ix=0;ix<9;++ix)
    normalize(_h[ix],1.,false);
      for(unsigned int ix=0;ix<3;++ix)
    normalize(_dalitz[ix]);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[9];
    Histo2DPtr _dalitz[3];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2021_I1940222);

}