rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BESII_2003_I623925

Mass distributions in $J/\psi\to\gamma K^+K^-$ and $J/\psi\to\gamma K_S^0K^0_S$
Experiment: BESII ()
Inspire ID: 623925
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Rev.D 68 (2003) 052003
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing J/psi, originally e+e-

Measurement of the kaon mass distribution in $J/\psi\to\gamma K^+K^-$ and $J/\psi\to\gamma K_S^0K^0_S$. The data were read from the plots in the paper and the backgrounds given subtracted.

Source code: BESII_2003_I623925.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 -> gamma K+K- KS0 KS0
10  class BESII_2003_I623925 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2003_I623925);
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==443);
24      declare(ufs, "UFS");
25      DecayedParticles PSI(ufs);
26      PSI.addStable(PID::K0S);
27      declare(PSI, "PSI");
28      // histos
29      for (unsigned int ix=0; ix<2; ++ix) {
30        book(_h[ix], 1, 1, 1+ix);
31      }
32    }
33
34
35    /// Perform the per-event analysis
36    void analyze(const Event& event) {
37      // find the J/psi decays
38      DecayedParticles PSI = apply<DecayedParticles>(event, "PSI");
39      // loop over particles
40      for (unsigned int ix=0; ix<PSI.decaying().size(); ++ix) {
41        unsigned int imode=0;
42        if (PSI.modeMatches(ix,3,mode1))      imode=0;
43        else if (PSI.modeMatches(ix,3,mode2)) imode=1;
44        else  continue;
45        const Particle& gam = PSI.decayProducts()[0].at( 22)[0];
46        _h[imode]->fill((PSI.decaying()[ix].mom()-gam.mom()).mass()/GeV);
47      }
48    }
49
50
51    /// Normalise histograms etc., after the run
52    void finalize() {
53      normalize(_h, 1.0, false);
54    }
55
56    /// @}
57
58
59    /// @name Histograms
60    /// @{
61    Histo1DPtr _h[2];
62    const map<PdgId,unsigned int> mode1 = { { 321,1}, { 321,1}, { 22,1}};
63    const map<PdgId,unsigned int> mode2 = { { 310,2}, { 22,1}};
64    /// @}
65
66
67  };
68
69
70  RIVET_DECLARE_PLUGIN(BESII_2003_I623925);
71
72}