Rivet analyses referenceBESIII_2022_I2167804$\psi(2S)\to \Lambda \bar{\Lambda}\eta$Experiment: BESIII (BEPC) Inspire ID: 2167804 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decay $\psi(2S)\to \Lambda \bar{\Lambda}\eta$. The data were read from the plots in the paper. It is also not clear that any resolution effects have been unfolded. Source code: BESIII_2022_I2167804.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) -> Lambda Lambdabar eta
10 class BESIII_2022_I2167804 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2167804);
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 psi(ufs);
25 psi.addStable(PID::PI0);
26 psi.addStable(PID::K0S);
27 psi.addStable(PID::ETA);
28 psi.addStable(PID::ETAPRIME);
29 psi.addStable(PID::OMEGA);
30 psi.addStable( 3122);
31 psi.addStable(-3122);
32 declare(psi, "psi");
33 for(unsigned int ix=0;ix<3;++ix)
34 book(_h[ix],1,1,1+ix);
35 book(_dalitz, "dalitz",50,2.,7.,50,2.,7.);
36 }
37
38
39 /// Perform the per-event analysis
40 void analyze(const Event& event) {
41 static const map<PdgId,unsigned int> & mode = { { 3122,1}, {-3122,1}, { 221,1} };
42 DecayedParticles psi = apply<DecayedParticles>(event, "psi");
43 // loop over particles
44 for(unsigned int ix=0;ix<psi.decaying().size();++ix) {
45 if(!psi.modeMatches(ix,3,mode)) continue;
46 const Particle & eta = psi.decayProducts()[ix].at( 221)[0];
47 const Particle & lam = psi.decayProducts()[ix].at( 3122)[0];
48 const Particle & lbar = psi.decayProducts()[ix].at(-3122)[0];
49 double mminus = (lbar.momentum()+eta.momentum()).mass2();
50 double mplus = (lam .momentum()+eta.momentum()).mass2();
51 _h[0]->fill(sqrt(mplus ));
52 _h[1]->fill(sqrt(mminus));
53 _h[2]->fill((lam .momentum()+lbar.momentum()).mass());
54 _dalitz->fill(mplus,mminus);
55 }
56 }
57
58
59 /// Normalise histograms etc., after the run
60 void finalize() {
61 for(unsigned int ix=0;ix<3;++ix)
62 normalize(_h[ix]);
63 normalize(_dalitz);
64 }
65
66 /// @}
67
68
69 /// @name Histograms
70 /// @{
71 Histo1DPtr _h[3];
72 Histo2DPtr _dalitz;
73 /// @}
74
75
76 };
77
78
79 RIVET_DECLARE_PLUGIN(BESIII_2022_I2167804);
80
81}
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