Rivet analyses referenceBESIII_2022_I2018236Radiative J/ψ→γη′π+π− decayExperiment: BESIII (BEPC) Inspire ID: 2018236 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the hadronic mass distribution in the decay J/ψ→γη′π+π−. 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_I2018236.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 -> gamma eta' pi+pi-
10 class BESIII_2022_I2018236 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2018236);
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==443);
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 declare(psi, "psi");
30 for(unsigned int ix=0;ix<2;++ix)
31 for(unsigned int iy=0;iy<2;++iy)
32 for(unsigned int iz=1;iz<2;++iz)
33 book(_h[ix][iy][iz],1+ix,1+iy,1+iz);
34 }
35
36
37 /// Perform the per-event analysis
38 void analyze(const Event& event) {
39 static const map<PdgId,unsigned int> & mode = { { 211,1}, {-211,1}, { 331,1} ,{22,1} };
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,4,mode)) continue;
44 const Particle & eta = psi.decayProducts()[ix].at( 331)[0];
45 const Particle & pip = psi.decayProducts()[ix].at( 211)[0];
46 const Particle & pim = psi.decayProducts()[ix].at(-211)[0];
47 double m1 = (pip.momentum()+pim.momentum()+eta.momentum()).mass();
48 double m2 = (pip.momentum()+pim.momentum()).mass();
49 for(unsigned int ix=0;ix<2;++ix) {
50 _h[0][ix][1]->fill(m1);
51 _h[1][ix][1]->fill(m2);
52 }
53 }
54 }
55
56
57 /// Normalise histograms etc., after the run
58 void finalize() {
59 for(unsigned int ix=0;ix<2;++ix)
60 for(unsigned int iy=0;iy<2;++iy)
61 for(unsigned int iz=1;iz<2;++iz)
62 normalize(_h[ix][iy][iz],1.,false);
63 }
64
65 /// @}
66
67
68 /// @name Histograms
69 /// @{
70 Histo1DPtr _h[2][2][2];
71 /// @}
72
73
74 };
75
76
77 RIVET_DECLARE_PLUGIN(BESIII_2022_I2018236);
78
79}
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