Rivet analyses referenceBESIII_2019_I1731057Dalitz plot analysis of J/ψ→K+K−π0Experiment: BESIII (BEPC) Inspire ID: 1731057 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decays J/ψ→K+K−π0 by BESIII. The data were read from the plots in the paper and therefore for most points the error bars are the size of the point. It is also not clear that any resolution/acceptance effects have been unfolded. Source code: BESIII_2019_I1731057.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/UnstableParticles.hh"
4#include "Rivet/Projections/DecayedParticles.hh"
5
6namespace Rivet {
7
8
9 /// @brief J/psi -> K+K-pi0
10 class BESIII_2019_I1731057 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2019_I1731057);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // Initialise and register projections
23 UnstableParticles ufs = UnstableParticles(Cuts::pid== 443);
24 declare(ufs, "UFS");
25 DecayedParticles PSI(ufs);
26 PSI.addStable(PID::PI0);
27 declare(PSI,"PSI");
28 // histos
29 for(unsigned int ix=0;ix<2;++ix) {
30 book(_h_KpKm [ix],1+ix,1,1);
31 book(_h_Kppi0[ix],1+ix,1,2);
32 }
33 book(_dalitz, "dalitz",50,0.,7.,50,0.0,7.);
34 }
35
36
37 /// Perform the per-event analysis
38 void analyze(const Event& event) {
39 static const map<PdgId,unsigned int> & mode = { { 321,1},{-321,1}, {111,1}};
40 DecayedParticles PSI = apply<DecayedParticles>(event, "PSI");
41 // loop over particles
42 for(unsigned int ix=0;ix<PSI.decaying().size();++ix) {
43 if (!PSI.modeMatches(ix,3,mode)) continue;
44 const Particle & Kp = PSI.decayProducts()[ix].at( 321)[0];
45 const Particle & Km = PSI.decayProducts()[ix].at(-321)[0];
46 const Particle & pi0 = PSI.decayProducts()[ix].at( 111)[0];
47 double mminus = (Km.momentum()+pi0.momentum()).mass2();
48 double mplus = (Kp.momentum()+pi0.momentum()).mass2();
49 double mneut = (Kp.momentum()+Km.momentum()).mass2();
50 _dalitz->fill(mplus,mminus);
51 mplus=sqrt(mplus);
52 mminus=sqrt(mminus);
53 mneut=sqrt(mneut);
54 _h_KpKm [0]->fill(mneut );
55 _h_Kppi0[0]->fill(mplus );
56 _h_Kppi0[0]->fill(mminus);
57 if(mplus>1.05 && mminus>1.05) {
58 _h_KpKm [1]->fill(mneut );
59 _h_Kppi0[1]->fill(mplus );
60 _h_Kppi0[1]->fill(mminus);
61 }
62 }
63 }
64
65
66 /// Normalise histograms etc., after the run
67 void finalize() {
68 for(unsigned int ix=0;ix<2;++ix) {
69 normalize(_h_KpKm [ix],1.,false);
70 normalize(_h_Kppi0[ix],1.,false);
71 }
72 normalize(_dalitz);
73 }
74
75 /// @}
76
77
78 /// @name Histograms
79 /// @{
80 Histo1DPtr _h_KpKm[2],_h_Kppi0[2];
81 Histo2DPtr _dalitz;
82 /// @}
83
84
85 };
86
87
88 RIVET_DECLARE_PLUGIN(BESIII_2019_I1731057);
89
90}
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