rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BABAR_2017_I1512302

Dalitz plot analysis of $J/\psi\to\pi^+\pi^-\pi^0$, $K^+K^-\pi^0$ and $K^0_SK^\pm\pi^\mp$
Experiment: BABAR (PEP-II)
Inspire ID: 1512302
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Rev.D 95 (2017) 7, 072007
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing J/psi, originally e+e-

Measurement of the mass distributions in the decays $J/\psi\to\pi^+\pi^-\pi^0$, $K^+K^-\pi^0$ and $K^0_SK^\pm\pi^\mp$ by BaBar. The data were read from the plots in the paper and therefore for some points the error bars are the size of the point. Also the sideband background from the plots has been subtracted. It is also not clear that any resolution effects have been unfolded.

Source code: BABAR_2017_I1512302.cc
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"

namespace Rivet {


  /// @brief J/psi dalitz decays
  class BABAR_2017_I1512302 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2017_I1512302);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::pid== 443);
      declare(ufs, "UFS");
      DecayedParticles PSI(ufs);
      PSI.addStable(PID::PI0);
      PSI.addStable(PID::K0S);
      declare(PSI,"PSI");
      // histos
      book(_h_pippim,1,1,1);
      book(_h_pippi0,1,1,2);
      book(_dalitz_3pi, "dalitz_3pi",50,0.,9.,50,0.0,9.);
      book(_h_KpKm ,2,1,1);
      book(_h_Kppi0,2,1,2);
      book(_dalitz_KpKmpi, "dalitz_KpKmpi",50,0.,7.,50,0.0,7.);
      book(_h_K0Kp ,3,1,1);
      book(_h_K0pip,3,1,2);
      book(_h_Kppip,3,1,3);
      book(_dalitz_K0Kppim, "dalitz_K0Kppim",50,0.,8.,50,0.,8.);
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode1   = { { 211,1},{-211,1}, {111,1}};
      static const map<PdgId,unsigned int> & mode2   = { { 321,1},{-321,1}, {111,1}};
      static const map<PdgId,unsigned int> & mode3   = { { 321,1},{-211,1}, {310,1}};
      static const map<PdgId,unsigned int> & mode3CC = { {-321,1},{ 211,1}, {310,1}};
      DecayedParticles PSI = apply<DecayedParticles>(event, "PSI");
      // loop over particles
      for(unsigned int ix=0;ix<PSI.decaying().size();++ix) {
	if (PSI.modeMatches(ix,3,mode1)) {
	  const Particle & pip = PSI.decayProducts()[ix].at( 211)[0];
	  const Particle & pim = PSI.decayProducts()[ix].at(-211)[0];
	  const Particle & pi0 = PSI.decayProducts()[ix].at( 111)[0];
	  double mminus = (pim.momentum()+pi0.momentum()).mass2();
	  double mplus  = (pip.momentum()+pi0.momentum()).mass2();
	  double mneut  = (pip.momentum()+pim.momentum()).mass2();
	  _h_pippim->fill(mneut );
	  _h_pippi0->fill(mplus );
	  _h_pippi0->fill(mminus);
	  _dalitz_3pi->fill(mplus,mminus);
	}
	else if (PSI.modeMatches(ix,3,mode2)) {
	  const Particle & Kp  = PSI.decayProducts()[ix].at( 321)[0];
	  const Particle & Km  = PSI.decayProducts()[ix].at(-321)[0];
	  const Particle & pi0 = PSI.decayProducts()[ix].at( 111)[0];
	  double mminus = (Km.momentum()+pi0.momentum()).mass2();
	  double mplus  = (Kp.momentum()+pi0.momentum()).mass2();
	  double mneut  = (Kp.momentum()+Km.momentum()).mass2();
	  _h_KpKm->fill(mneut );
	  _h_Kppi0->fill(mplus );
	  _h_Kppi0->fill(mminus);
	  _dalitz_KpKmpi->fill(mplus,mminus);
	}
	else {
	  int sign =1;
	  if     (PSI.modeMatches(ix,3,mode3  )) sign= 1;
	  else if(PSI.modeMatches(ix,3,mode3CC)) sign=-1;
	  else continue;
	  const Particle & Kp  = PSI.decayProducts()[ix].at( sign*321)[0];
	  const Particle & pim = PSI.decayProducts()[ix].at(-sign*211)[0];
	  const Particle & K0  = PSI.decayProducts()[ix].at(      310)[0];
	  double mplus  = (Kp.momentum()  +  K0.momentum()).mass2();
	  double mminus = (K0.momentum()  + pim.momentum()).mass2();
	  double mKK    = (Kp.momentum()  +  K0.momentum()).mass2();
	  _h_K0Kp ->fill(mKK);
	  _h_Kppip->fill(mplus);
	  _h_K0pip->fill(mminus);
	  _dalitz_K0Kppim->fill(mplus,mminus);
	}
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_pippim,1.,false);
      normalize(_h_pippi0,1.,false);
      normalize(_dalitz_3pi);
      normalize(_h_KpKm,1.,false);
      normalize(_h_Kppi0,1.,false);
      normalize(_dalitz_KpKmpi);
      normalize(_h_Kppip);
      normalize(_h_K0pip);
      normalize(_h_K0Kp );
      normalize(_dalitz_K0Kppim);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_pippim,_h_pippi0;
    Histo2DPtr _dalitz_3pi;
    Histo1DPtr _h_KpKm,_h_Kppi0;
    Histo2DPtr _dalitz_KpKmpi;
    Histo1DPtr _h_Kppip,_h_K0pip,_h_K0Kp;
    Histo2DPtr _dalitz_K0Kppim;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BABAR_2017_I1512302);

}