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BESIII_2022_I2102455

Mass distributions in $D^+$ and $D^0$ decays to pions
Experiment: BESIII ()
Inspire ID: 2102455
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References: Beams: * *
Beam energies: ANY
    No run details listed

Measurement of the mass distributions in $D^+$ and $D^0$ decays to pions by the BESIII collaboration. 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_2022_I2102455.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"

namespace Rivet {


  /// @brief D0/D+ to pions
  class BESIII_2022_I2102455 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2102455);


    /// @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
      vector<unsigned int> nHist = {3,7,9,14,2,2,5,4,11};
      for(unsigned int ix=0;ix<9;++ix) {
	_h.push_back(vector<Histo1DPtr>());
	for(unsigned int iy=0;iy<nHist[ix];++iy) {
	  Histo1DPtr tmp;
	  book(tmp,ix+1,1,iy+1);
	  _h[ix].push_back(tmp);
	}
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // define the decay mode
      static const map<PdgId,unsigned int> & mode1   = { { 211,1}, { -211,1}, { 111,1} };
      static const map<PdgId,unsigned int> & mode2   = { { 211,1}, { -211,1}, { 111,2} };
      static const map<PdgId,unsigned int> & mode3   = { { 211,2}, { -211,2}, { 111,1} };
      static const map<PdgId,unsigned int> & mode4   = { { 211,2}, { -211,2}, { 111,2} };
      static const map<PdgId,unsigned int> & mode5   = { { 211,2}, { -211,1}};
      static const map<PdgId,unsigned int> & mode5CC = { { 211,1}, { -211,2}};
      static const map<PdgId,unsigned int> & mode6   = { { 211,1}, {  111,2}};
      static const map<PdgId,unsigned int> & mode6CC = { {-211,1}, {  111,2}};
      static const map<PdgId,unsigned int> & mode7   = { { 211,2}, { -211,1}, { 111,1} };
      static const map<PdgId,unsigned int> & mode7CC = { { 211,1}, { -211,2}, { 111,1} };
      static const map<PdgId,unsigned int> & mode8   = { { 211,3}, { -211,2}};
      static const map<PdgId,unsigned int> & mode8CC = { { 211,2}, { -211,3}};
      static const map<PdgId,unsigned int> & mode9   = { { 211,3}, { -211,2}, { 111,1} };
      static const map<PdgId,unsigned int> & mode9CC = { { 211,2}, { -211,3}, { 111,1} };
      DecayedParticles DD = apply<DecayedParticles>(event, "DD");
      // loop over particles
      for(unsigned int ix=0;ix<DD.decaying().size();++ix) {
	int sign = DD.decaying()[ix].pid()/DD.decaying()[ix].abspid();
	// D0 -> pi+ pi- pi0
	if ( DD.modeMatches(ix,3,mode1)) {
	  const Particles & pip = DD.decayProducts()[ix].at( sign*211);
	  const Particles & pim = DD.decayProducts()[ix].at(-sign*211);
	  const Particles & pi0 = DD.decayProducts()[ix].at(      111);
	  // KS0 veto
	  double mpm = (pip[0].momentum()+pim[0].momentum()).mass();
	  if(mpm>.468 && mpm<.528) continue;
	  _h[0][0]->fill((pip[0].momentum()+pi0[0].momentum()).mass());
	  _h[0][1]->fill((pim[0].momentum()+pi0[0].momentum()).mass());
	  _h[0][2]->fill(mpm);
	}
	// D0 -> pi+ pi- 2pi0 
	else if ( DD.modeMatches(ix,4,mode2)) {
	  const Particles & pip = DD.decayProducts()[ix].at( sign*211);
	  const Particles & pim = DD.decayProducts()[ix].at(-sign*211);
	  const Particles & pi0 = DD.decayProducts()[ix].at(      111);
	  // KS0 veto
	  FourMomentum ppm = pip[0].momentum()+pim[0].momentum(); 
	  double mpm = ppm.mass();
	  if(mpm>.468 && mpm<.528) continue;
	  FourMomentum p00 = pi0[0].momentum()+pi0[1].momentum();
	  double m00 = p00.mass();
	  if(m00>.428 && m00<.548) continue;
	  _h[1][0]->fill((pip[0].momentum()+pi0[0].momentum()).mass());
	  _h[1][0]->fill((pip[0].momentum()+pi0[1].momentum()).mass());
	  _h[1][1]->fill((pim[0].momentum()+pi0[0].momentum()).mass());
	  _h[1][1]->fill((pim[0].momentum()+pi0[1].momentum()).mass());
	  _h[1][2]->fill(mpm);
	  _h[1][3]->fill((pi0[0].momentum()+pi0[1].momentum()).mass());
	  _h[1][4]->fill((p00+pip[0].momentum()).mass());
	  _h[1][5]->fill((p00+pim[0].momentum()).mass());
	  _h[1][6]->fill((ppm+pi0[0].momentum()).mass());
	  _h[1][6]->fill((ppm+pi0[1].momentum()).mass());
	}
	// D0 -> 2pi+ 2pi- pi0 
	else if ( DD.modeMatches(ix,5,mode3)) {
	  const Particles & pip = DD.decayProducts()[ix].at( sign*211);
	  const Particles & pim = DD.decayProducts()[ix].at(-sign*211);
	  const Particles & pi0 = DD.decayProducts()[ix].at(      111);
	  // pi+ pi- masses and KS0 veto
	  double mpm[4];
	  bool veto=false;
	  for(unsigned int ix=0;ix<2;++ix) {
	    for(unsigned int iy=0;iy<2;++iy) {
	      mpm[2*ix+iy] = (pip[ix].momentum()+pim[iy].momentum()).mass(); 
	      if(mpm[2*ix+iy]>.468 && mpm[2*ix+iy]<.528) veto=true;
	    }
	  }
	  if(veto) continue;
	  // fill the histograms
	  FourMomentum ppp = pip[0].momentum()+pip[1].momentum();
	  FourMomentum pmm = pim[0].momentum()+pim[1].momentum();
	  for(unsigned int ix=0;ix<2;++ix) {
	    _h[2][0]->fill((pip[ix].momentum()+pi0[0].momentum()).mass());
	    _h[2][1]->fill((pim[ix].momentum()+pi0[0].momentum()).mass());
	    _h[2][3]->fill((ppp+pim[ix].momentum()).mass());
	    _h[2][4]->fill((pmm+pip[ix].momentum()).mass());
	    _h[2][6]->fill((ppp+pim[ix].momentum()+pi0[0].momentum()).mass());
	    _h[2][7]->fill((pmm+pip[ix].momentum()+pi0[0].momentum()).mass());
	    for(unsigned int iy=0;iy<2;++iy) {
	      _h[2][2]->fill(mpm[2*ix+iy]);
	      _h[2][5]->fill((pip[ix].momentum()+pim[iy].momentum()+pi0[0].momentum()).mass()); 
	    }
	  }
	  _h[2][8]->fill((ppp+pmm).mass());
	}
	// D0 -> 2pi+ 2pi- pi0 
	else if ( DD.modeMatches(ix,6,mode4)) {
	  const Particles & pip = DD.decayProducts()[ix].at( sign*211);
	  const Particles & pim = DD.decayProducts()[ix].at(-sign*211);
	  const Particles & pi0 = DD.decayProducts()[ix].at(      111);
	  // pi+ pi- masses and KS0 veto
	  double mpm[4];
	  bool veto=false;
	  for(unsigned int ix=0;ix<2;++ix) {
	    for(unsigned int iy=0;iy<2;++iy) {
	      mpm[2*ix+iy] = (pip[ix].momentum()+pim[iy].momentum()).mass(); 
	      if(mpm[2*ix+iy]>.468 && mpm[2*ix+iy]<.528) veto=true;
	    }
	  }
	  if(veto) continue;
	  FourMomentum p00 = pi0[0].momentum()+pi0[1].momentum();
	  double m00 = p00.mass();
	  if(m00>.428 && m00<.548) continue;
	  // fill the histograms
	  _h[3][3]->fill(m00);
	  FourMomentum ppp = pip[0].momentum()+pip[1].momentum();
	  FourMomentum pmm = pim[0].momentum()+pim[1].momentum();
	  for(unsigned int ix=0;ix<2;++ix) {
	    for(unsigned int i0=0;i0<2;++i0) {
	      _h[3][ 0]->fill((pip[ix].momentum()+pi0[i0].momentum()).mass());
	      _h[3][ 1]->fill((pim[ix].momentum()+pi0[i0].momentum()).mass());
	      _h[3][ 7]->fill((ppp+pim[ix].momentum()+pi0[i0].momentum()).mass());
	      _h[3][ 8]->fill((pmm+pip[ix].momentum()+pi0[i0].momentum()).mass());
	      _h[3][11]->fill((ppp+pim[ix].momentum()+p00).mass());
	      _h[3][12]->fill((pmm+pip[ix].momentum()+p00).mass());
	      _h[3][13]->fill((pmm+pi0[ix].momentum()+ppp).mass());
	      for(unsigned int iy=0;iy<2;++iy)
		_h[3][6]->fill((pip[ix].momentum()+pim[iy].momentum()+pi0[i0].momentum()).mass());
	    }
	    _h[3][4]->fill((ppp+pim[ix].momentum()).mass());
	    _h[3][5]->fill((pmm+pip[ix].momentum()).mass());
	    for(unsigned int iy=0;iy<2;++iy) {
	      _h[3][ 2]->fill(mpm[2*ix+iy]);
	      _h[3][10]->fill((pip[ix].momentum()+pim[iy].momentum()+p00).mass());
	    }
	  }
	  _h[3][9]->fill((ppp+pmm).mass());
	}
	// D+ -> 2pi+ pi- 
	else if ( DD.modeMatches(ix,3,mode5  ) ||
		  DD.modeMatches(ix,3,mode5CC)) {
	  const Particles & pip = DD.decayProducts()[ix].at( sign*211);
	  const Particles & pim = DD.decayProducts()[ix].at(-sign*211);
	  // pi+ pi- masses and KS0 veto
	  double mpm[2];
	  bool veto=false;
	  for(unsigned int ix=0;ix<2;++ix) {
	    mpm[ix] = (pip[ix].momentum()+pim[0].momentum()).mass(); 
	    if(mpm[ix]>.468 && mpm[ix]<.528) veto=true;
	  }
	  if(veto) continue;
	  _h[4][0]->fill((pip[0].momentum()+pip[1].momentum()).mass());
	  for(unsigned int ix=0;ix<2;++ix) {
	    _h[4][1]->fill(mpm[ix]);
	  }
	}
	// D+ -> pi+ 2pi0 
	else if ( DD.modeMatches(ix,3,mode6  ) ||
		  DD.modeMatches(ix,3,mode6CC)) {
	  const Particles & pip = DD.decayProducts()[ix].at( sign*211);
	  const Particles & pi0 = DD.decayProducts()[ix].at(      111);
	  FourMomentum p00 = pi0[0].momentum()+pi0[1].momentum();
	  double m00 = p00.mass();
	  if(m00>.428 && m00<.548) continue;
	  // fill the histograms
	  _h[5][1]->fill(m00);
	  for(unsigned int ix=0;ix<2;++ix) {
	    _h[5][0]->fill((pip[0].momentum()+pi0[ix].momentum()).mass());
	  }
	}
	// D+ -> 2pi+ pi- pi0
	else if ( DD.modeMatches(ix,4,mode7  ) ||
		  DD.modeMatches(ix,4,mode7CC)) {
	  const Particles & pip = DD.decayProducts()[ix].at( sign*211);
	  const Particles & pim = DD.decayProducts()[ix].at(-sign*211);
	  const Particles & pi0 = DD.decayProducts()[ix].at(      111);
	  // pi+ pi- masses and KS0 veto
	  double mpm[2];
	  bool veto=false;
	  for(unsigned int ix=0;ix<2;++ix) {
	    mpm[ix] = (pip[ix].momentum()+pim[0].momentum()).mass(); 
	    if(mpm[ix]>.468 && mpm[ix]<.528) veto=true;
	  }
	  if(veto) continue;
	  _h[6][1]->fill((pim[0].momentum()+pi0[0].momentum()).mass());
	  _h[6][3]->fill((pim[0].momentum()+pip[0].momentum()+pip[1].momentum()).mass());
	  for(unsigned int ix=0;ix<2;++ix) {
	    _h[6][0]->fill((pip[ix].momentum()+pi0[0].momentum()).mass());
	    _h[6][2]->fill(mpm[ix]);
	    _h[6][4]->fill((pip[ix].momentum()+pim[0].momentum()+pi0[0].momentum()).mass());
	  }
	}
	// D+ -> 3pi+ 2pi- 
	else if ( DD.modeMatches(ix,5,mode8  ) ||
		  DD.modeMatches(ix,5,mode8CC)) {
	  const Particles & pip = DD.decayProducts()[ix].at( sign*211);
	  const Particles & pim = DD.decayProducts()[ix].at(-sign*211);
	  // pi+ pi- masses and KS0 veto
	  double mpm[3][2];
	  bool veto=false;
	  for(unsigned int ix=0;ix<3;++ix) {
	    for(unsigned int iy=0;iy<2;++iy) {
	      mpm[ix][iy] = (pip[ix].momentum()+pim[iy].momentum()).mass(); 
	      if(mpm[ix][iy]>.468 && mpm[ix][iy]<.528) veto=true;
	    }
	  }
	  if(veto) continue;
	  FourMomentum pppp = pip[0].momentum()+pip[1].momentum()+pip[2].momentum();
	  FourMomentum pmm  = pim[0].momentum()+pim[1].momentum();
	  for(unsigned int ix=0;ix<3;++ix) {
	    _h[7][2]->fill((pmm+pip[ix].momentum()).mass());
	    for(unsigned int iy=0;iy<2;++iy) {
	      _h[7][0]->fill(mpm[ix][iy]);
	      _h[7][1]->fill((pppp-pip[ix].momentum()+pim[iy].momentum()).mass());
	    }
	  }
	  for(unsigned int iy=0;iy<2;++iy)
	    _h[7][3]->fill((pppp+pim[iy].momentum()).mass());
	}
	// D+ -> 3pi+ 2pi- pi0
	else if ( DD.modeMatches(ix,6,mode9  ) ||
		  DD.modeMatches(ix,6,mode9CC)) {
	  const Particles & pip = DD.decayProducts()[ix].at( sign*211);
	  const Particles & pim = DD.decayProducts()[ix].at(-sign*211);
	  const Particles & pi0 = DD.decayProducts()[ix].at(      111);
	  // pi+ pi- masses and KS0 veto
	  double mpm[3][2];
	  bool veto=false;
	  for(unsigned int ix=0;ix<3;++ix) {
	    for(unsigned int iy=0;iy<2;++iy) {
	      mpm[ix][iy] = (pip[ix].momentum()+pim[iy].momentum()).mass(); 
	      if(mpm[ix][iy]>.468 && mpm[ix][iy]<.528) veto=true;
	    }
	  }
	  if(veto) continue;
	  FourMomentum pppp = pip[0].momentum()+pip[1].momentum()+pip[2].momentum();
	  FourMomentum pmm  = pim[0].momentum()+pim[1].momentum();
	  FourMomentum pcharged = pppp+pmm;
	  _h[8][9]->fill(pcharged.mass());
	  for(unsigned int ix=0;ix<3;++ix) {
	    _h[8][0]->fill((pip[ix].momentum()+pi0[0].momentum()).mass());
	    FourMomentum pmmp = (pmm+pip[ix].momentum()); 
	    _h[8][ 4]->fill(pmmp.mass()); 
	    _h[8][ 7]->fill((pmmp+pi0[0].momentum()).mass());
	    _h[8][ 8]->fill((pcharged-pip[ix].momentum()).mass());
	    _h[8][10]->fill((pcharged-pip[ix].momentum()+pi0[0].momentum()).mass());
	    for(unsigned int iy=0;iy<2;++iy) {
	      _h[8][2]->fill(mpm[ix][iy]);
	      FourMomentum pppm = (pppp-pip[ix].momentum()+pim[iy].momentum()); 
	      _h[8][3]->fill(pppm.mass()); 
	      _h[8][6]->fill((pppm+pi0[0].momentum()).mass());
	      _h[8][5]->fill((pip[ix].momentum()+pim[iy].momentum()+pi0[0].momentum()).mass());
	    }
	  }
	  for(unsigned int iy=0;iy<2;++iy) {
	    _h[8][1]->fill((pim[iy].momentum()+pi0[0].momentum()).mass());
	  }
	}
      }
    }


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

    /// @}


    /// @name Histograms
    /// @{
    vector<vector<Histo1DPtr> > _h;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2022_I2102455);

}