Rivet analyses referenceBESIII_2017_I1469067Kinematic distributions in the decays $\eta^\prime\to\pi^+\pi^-\pi^0$ and $\pi\pi^0\pi^0$Experiment: BESIII (BEPC) Inspire ID: 1469067 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of kinematic distributions in the decay $\eta^\prime\to\eta\pi^0\pi^0$. Data was read from the graphs and the simulated background from the plots subtracted. Source code: BESIII_2017_I1469067.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 eta' -> pions
10 class BESIII_2017_I1469067 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2017_I1469067);
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==PID::ETAPRIME);
24 declare(ufs, "UFS");
25 DecayedParticles ETA(ufs);
26 ETA.addStable(PID::PI0);
27 ETA.addStable(PID::K0S);
28 ETA.addStable(PID::ETA);
29 declare(ETA, "ETA");
30 // histograms
31 for(unsigned int ix=0;ix<4;++ix) {
32 book(_h[ix],1,1,1+ix);
33 }
34 }
35
36
37 /// Perform the per-event analysis
38 void analyze(const Event& event) {
39 static const map<PdgId,unsigned int> & mode1 = { {211,1}, {-211,1}, {111,1} };
40 static const map<PdgId,unsigned int> & mode2 = { {111,3} };
41 DecayedParticles ETA = apply<DecayedParticles>(event, "ETA");
42 // loop over particles
43 for(unsigned int ix=0;ix<ETA.decaying().size();++ix) {
44 // select right decay mode
45 if ( ETA.modeMatches(ix,3,mode1)) {
46 const Particle & pi0 = ETA.decayProducts()[ix].at( 111)[0];
47 const Particle & pip = ETA.decayProducts()[ix].at( 211)[0];
48 const Particle & pim = ETA.decayProducts()[ix].at(-211)[0];
49 _h[0]->fill((pip.momentum()+pim.momentum()).mass());
50 _h[1]->fill((pip.momentum()+pi0.momentum()).mass());
51 _h[2]->fill((pim.momentum()+pi0.momentum()).mass());
52 }
53 else if ( ETA.modeMatches(ix,3,mode2)) {
54 const Particles & pi0 = ETA.decayProducts()[ix].at(111);
55 for(unsigned int ix=0;ix<3;++ix) {
56 for(unsigned int iy=ix+1;iy<3;++iy)
57 _h[3]->fill((pi0[ix].momentum()+pi0[iy].momentum()).mass());
58 }
59 }
60 }
61 }
62
63
64 /// Normalise histograms etc., after the run
65 void finalize() {
66 // normalize the histograms
67 for(unsigned int ix=0;ix<4;++ix)
68 normalize(_h[ix]);
69 }
70
71 /// @}
72
73
74 /// @name Histograms
75 /// @{
76 Histo1DPtr _h[4];
77 /// @}
78
79
80 };
81
82
83 RIVET_DECLARE_PLUGIN(BESIII_2017_I1469067);
84
85}
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