Rivet analyses referenceBESIII_2012_I1088606Mass distributions in $J/\psi$ and $\psi(2S)$ to $\pi^+\pi^-\pi^0$Experiment: BESIII (BEPC) Inspire ID: 1088606 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the $\pi\pi$ mass distribution in the decays $J/\psi$ and $\psi(2S)$ to $\pi^+\pi^-\pi^0$ be BES. N.B. data read from plots and may not be corrected. Source code: BESIII_2012_I1088606.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 and psi(2S) -> pi+pi-pi0
10 class BESIII_2012_I1088606 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2012_I1088606);
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 or 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 declare(psi, "psi");
30 book(_h_pipi[0],1,1,1);
31 book(_h_pipi[1],1,1,2);
32 book(_dalitz[0], "dalitz_Jpsi" ,50,0.,9. ,50,0.0, 9.);
33 book(_dalitz[1], "dalitz_psi2S",50,0.,14.,50,0.0,14.);
34 }
35
36 /// Perform the per-event analysis
37 void analyze(const Event& event) {
38 static const map<PdgId,unsigned int> & mode = { { 211,1}, {-211,1}, { 111,1} };
39 DecayedParticles psi = apply<DecayedParticles>(event, "psi");
40 // loop over particles
41 for(unsigned int ix=0;ix<psi.decaying().size();++ix) {
42 if(!psi.modeMatches(ix,3,mode)) continue;
43 const Particles & pi0 = psi.decayProducts()[ix].at( 111);
44 const Particles & pip = psi.decayProducts()[ix].at( 211);
45 const Particles & pim = psi.decayProducts()[ix].at(-211);
46 double mminus = (pim[0].momentum()+pi0[0].momentum()).mass2();
47 double mplus = (pip[0].momentum()+pi0[0].momentum()).mass2();
48 double mneut = (pip[0].momentum()+pim[0].momentum()).mass2();
49 unsigned int iloc = psi.decaying()[ix].pid()/100000;
50 _h_pipi[iloc]->fill(sqrt(mneut ));
51 _h_pipi[iloc]->fill(sqrt(mplus ));
52 _h_pipi[iloc]->fill(sqrt(mminus));
53 _dalitz[iloc]->fill(mplus,mminus);
54 }
55 }
56
57
58 /// Normalise histograms etc., after the run
59 void finalize() {
60 for(unsigned int ix=0;ix<2;++ix) {
61 normalize(_h_pipi [ix]);
62 normalize(_dalitz[ix]);
63 }
64 }
65
66 /// @}
67
68
69 /// @name Histograms
70 /// @{
71 Histo1DPtr _h_pipi[2];
72 Histo2DPtr _dalitz[2];
73 /// @}
74
75
76 };
77
78
79 RIVET_DECLARE_PLUGIN(BESIII_2012_I1088606);
80
81}
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