rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BESIII_2020_I1799437

Dalitz plot analysis of $D^0\to K^0_SK^+K^-$
Experiment: BESIII (BEPC)
Inspire ID: 1799437
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References: Beams: * *
Beam energies: ANY
Run details:
  • Any process producing D0

Measurement of Kinematic distributions in the decay $D^0\to K^0_SK^+K^-$ by BES. The data were read from the plots in the paper. Resolution/acceptance effects have been not unfolded. Given the agreement with the model in the paper this analysis should only be used for qualitative studies.

Source code: BESIII_2020_I1799437.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
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"

namespace Rivet {


  /// @brief D0 -> K_S0 K+ K-
  class BESIII_2020_I1799437 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2020_I1799437);


    /// @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_K0Km,1,1,3);
      book(_h_K0Kp,1,1,2);
      book(_h_KpKm,1,1,1);
      book(_dalitz, "dalitz",50,0.9,1.9,50,0.9,1.9);
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode   = { { 321,1},{-321,1}, { 310,1}};
      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 & K0 = D0.decayProducts()[ix].at(310);
	const Particles & Kp = D0.decayProducts()[ix].at( sign*321);
	const Particles & Km = D0.decayProducts()[ix].at(-sign*321);
	double mminus = (Km[0].momentum()+K0[0].momentum() ).mass2();
	double mplus  = (Kp[0].momentum()+K0[0].momentum() ).mass2();
	double mKK  = (Kp[0].momentum()+Km[0].momentum()).mass2();
	_h_K0Kp->fill(mplus);
	_h_K0Km->fill(mminus);
	_h_KpKm->fill(mKK);
	_dalitz->fill(mKK,mplus); 
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_K0Km);
      normalize(_h_K0Kp);
      normalize(_h_KpKm);
      normalize(_dalitz);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_K0Km,_h_KpKm,_h_K0Kp;
    Histo2DPtr _dalitz;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2020_I1799437);

}