Rivet analyses referenceBES_2001_I556330$J/\psi\to p \bar{p}\eta$Experiment: BES (BEPC) Inspire ID: 556330 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decay $J/\psi\to p \bar{p}\eta$. The data were read from the plots in the paper and may not be corrected for detector efficiency or backgrounds. Source code: BES_2001_I556330.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 -> p pbar eta
10 class BES_2001_I556330 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BES_2001_I556330);
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 book(_h[ix],1+ix,1,1);
32 book(_dalitz, "dalitz",50,2.,5.,50,2.,5.);
33 }
34
35
36 /// Perform the per-event analysis
37 void analyze(const Event& event) {
38 static const map<PdgId,unsigned int> & mode = { { 2212,1}, {-2212,1}, { 221,1} };
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 & eta = psi.decayProducts()[ix].at( 221);
44 const Particles & pp = psi.decayProducts()[ix].at( 2212);
45 const Particles & pbar = psi.decayProducts()[ix].at(-2212);
46 double mminus = (pbar[0].momentum()+eta[0].momentum()).mass2();
47 double mplus = (pp [0].momentum()+eta[0].momentum()).mass2();
48 _h[0]->fill(sqrt(mplus ));
49 _h[0]->fill(sqrt(mminus));
50 _h[1]->fill((pp [0].momentum()+pbar[0].momentum()).mass());
51 _dalitz->fill(mplus,mminus);
52 }
53 }
54
55
56 /// Normalise histograms etc., after the run
57 void finalize() {
58 normalize(_dalitz);
59 for(unsigned int ix=0;ix<2;++ix)
60 normalize(_h[ix]);
61 }
62
63 /// @}
64
65
66 /// @name Histograms
67 /// @{
68 Histo1DPtr _h[2];
69 Histo2DPtr _dalitz;
70 /// @}
71
72
73 };
74
75
76 RIVET_DECLARE_PLUGIN(BES_2001_I556330);
77
78}
|