Rivet analyses referenceBESIII_2020_I1771616Dalitz plot analysis of $\psi(2S)\to K^+K^-\eta$Experiment: BESIII (BEPC) Inspire ID: 1771616 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decay $\psi(2S)\to K^+K^-\eta$. The data were read from the plots in the paper. Also the sideband background from the plots has been subtracted. It is also not clear that any resolution effects have been unfolded. Source code: BESIII_2020_I1771616.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 psi(2S) -> K+K- eta
10 class BESIII_2020_I1771616 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2020_I1771616);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 UnstableParticles ufs = UnstableParticles(Cuts::pid==100443);
23 declare(ufs, "UFS");
24 DecayedParticles psi2S(ufs);
25 psi2S.addStable(PID::PI0);
26 psi2S.addStable(PID::K0S);
27 psi2S.addStable(PID::ETA);
28 psi2S.addStable(PID::ETAPRIME);
29 declare(psi2S, "psi2S");
30 for(unsigned int ix=0;ix<3;++ix)
31 book(_h[ix],1,1,1+ix);
32 book(_dalitz, "dalitz",50,0.,11.,50,0.0,11.);
33 }
34
35
36 /// Perform the per-event analysis
37 void analyze(const Event& event) {
38 static const map<PdgId,unsigned int> & mode = { { 321,1}, {-321,1}, { 221,1} };
39 DecayedParticles psi2S = apply<DecayedParticles>(event, "psi2S");
40 // loop over particles
41 for(unsigned int ix=0;ix<psi2S.decaying().size();++ix) {
42 if(!psi2S.modeMatches(ix,3,mode)) continue;
43 const Particles & eta = psi2S.decayProducts()[ix].at( 221);
44 const Particles & Kp = psi2S.decayProducts()[ix].at( 321);
45 const Particles & Km = psi2S.decayProducts()[ix].at(-321);
46 double mminus = (Km[0].momentum()+eta[0].momentum()).mass2();
47 double mplus = (Kp[0].momentum()+eta[0].momentum()).mass2();
48 double mneut = (Kp[0].momentum()+Km [0].momentum()).mass2();
49 _h[0]->fill(sqrt(mneut ));
50 _h[1]->fill(sqrt(mplus ));
51 _h[2]->fill(sqrt(mminus));
52 _dalitz->fill(mplus,mminus);
53 }
54 }
55
56
57 /// Normalise histograms etc., after the run
58 void finalize() {
59 for(unsigned int ix=0;ix<3;++ix)
60 normalize(_h[ix]);
61 normalize(_dalitz);
62 }
63
64 /// @}
65
66
67 /// @name Histograms
68 /// @{
69 Histo1DPtr _h[3];
70 Histo2DPtr _dalitz;
71 /// @}
72
73
74 };
75
76
77 RIVET_DECLARE_PLUGIN(BESIII_2020_I1771616);
78
79}
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