Rivet analyses referenceBES_2005_I689969Mass distributions in $\psi(2S)\to\pi^+\pi^-\pi^0$Experiment: BES (BEPC) Inspire ID: 689969 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the $\pi\pi$ mass distribution in the decays $\psi(2S)\to\pi^+\pi^-\pi^0$ be BES. N.B. data read from plots and may not be corrected. Source code: BES_2005_I689969.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) -> pi+pi-pi0
10 class BES_2005_I689969 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BES_2005_I689969);
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 book(_h_pipi,1,1,1);
31 book(_dalitz, "dalitz",50,0.,14.,50,0.0,14.);
32 }
33
34
35 /// Perform the per-event analysis
36 void analyze(const Event& event) {
37 static const map<PdgId,unsigned int> & mode = { { 211,1}, {-211,1}, { 111,1} };
38 DecayedParticles psi2S = apply<DecayedParticles>(event, "psi2S");
39 // loop over particles
40 for(unsigned int ix=0;ix<psi2S.decaying().size();++ix) {
41 if(!psi2S.modeMatches(ix,3,mode)) continue;
42 const Particles & pi0 = psi2S.decayProducts()[ix].at( 111);
43 const Particles & pip = psi2S.decayProducts()[ix].at( 211);
44 const Particles & pim = psi2S.decayProducts()[ix].at(-211);
45 double mminus = (pim[0].momentum()+pi0[0].momentum()).mass2();
46 double mplus = (pip[0].momentum()+pi0[0].momentum()).mass2();
47 double mneut = (pip[0].momentum()+pim[0].momentum()).mass2();
48 _h_pipi->fill(sqrt(mneut ));
49 _h_pipi->fill(sqrt(mplus ));
50 _h_pipi->fill(sqrt(mminus));
51 _dalitz->fill(mplus,mminus);
52 }
53 }
54
55
56 /// Normalise histograms etc., after the run
57 void finalize() {
58 normalize(_h_pipi);
59 normalize(_dalitz);
60 }
61
62 /// @}
63
64
65 /// @name Histograms
66 /// @{
67 Histo1DPtr _h_pipi;
68 Histo2DPtr _dalitz;
69 /// @}
70
71
72 };
73
74
75 RIVET_DECLARE_PLUGIN(BES_2005_I689969);
76
77}
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