Rivet analyses referenceBESII_2007_I763951Mass distributions in $\psi(2S)\to\gamma\pi^+\pi^-$ and $\psi(2S)\to\gamma K^+K^-$Experiment: BESII (BEPC) Inspire ID: 763951 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the pion pair mass distribution in $\psi(2S)\to\gamma\pi^+\pi^-$ and $\psi(2S)\to\gamma K^+K^-$. The data were read from the plots in the paper and the backgrounds given subtracted. Source code: BESII_2007_I763951.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) -> gamma pi+pi- / K+K-
10 class BESII_2007_I763951 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2007_I763951);
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::abspid==100443);
24 declare(ufs, "UFS");
25 DecayedParticles PSI(ufs);
26 PSI.addStable(PID::ETA);
27 PSI.addStable(PID::PI0);
28 declare(PSI, "PSI");
29 // histos
30 for (unsigned int ix=0;ix<2;++ix) {
31 book(_h[ix],1+ix,1,1);
32 }
33 }
34
35
36 /// Perform the per-event analysis
37 void analyze(const Event& event) {
38 // find the J/psi decays
39 DecayedParticles PSI = apply<DecayedParticles>(event, "PSI");
40 // loop over particles
41 for (unsigned int ix=0; ix<PSI.decaying().size(); ++ix) {
42 unsigned int imode=0;
43 if (PSI.modeMatches(ix,3,mode1)) imode=0;
44 else if (PSI.modeMatches(ix,3,mode2)) imode=1;
45 else continue;
46 const Particle& gam = PSI.decayProducts()[0].at( 22)[0];
47 _h[imode]->fill((PSI.decaying()[ix].mom()-gam.mom()).mass());
48 }
49 }
50
51
52 /// Normalise histograms etc., after the run
53 void finalize() {
54 normalize(_h, 1.0, false);
55 }
56
57 /// @}
58
59
60 /// @name Histograms
61 /// @{
62 Histo1DPtr _h[2];
63 const map<PdgId,unsigned int> mode1 = { { 211,1}, {-211,1}, { 22,1}};
64 const map<PdgId,unsigned int> mode2 = { { 321,1}, {-321,1}, { 22,1}};
65 /// @}
66
67
68 };
69
70
71 RIVET_DECLARE_PLUGIN(BESII_2007_I763951);
72
73}
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