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Rivet analyses reference

BELLE_2014_I1282602

Cross section for $e^+e^-\to J/\psi K^+K^-$ at energies between 4.175 and 5.975 GeV
Experiment: BELLE (KEKB)
Inspire ID: 1282602
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D89 (2014) 072015, 2014
Beams: e+ e-
Beam energies: (2.1, 2.1); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.4, 2.4); (2.4, 2.4); (2.4, 2.4); (2.4, 2.4); (2.5, 2.5); (2.5, 2.5); (2.5, 2.5); (2.5, 2.5); (2.6, 2.6); (2.6, 2.6); (2.6, 2.6); (2.6, 2.6); (2.7, 2.7); (2.7, 2.7); (2.7, 2.7); (2.7, 2.7); (2.8, 2.8); (2.8, 2.8); (2.8, 2.8); (2.9, 2.9); (2.9, 2.9); (2.9, 2.9); (2.9, 2.9); (3.0, 3.0); (3.0, 3.0) GeV
Run details:
  • e+e- to hadrons

Measurement of the cross section for $e^+e^-\to J/\psi K^+K^-$ at energies between 4.175 and 5.975 GeV using radiative return by BELLE. The paper also includes $J\psi K^0_SK^0_S$ but the data is a confidence limit and is therefore not implemented. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Source code: BELLE_2014_I1282602.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/UnstableParticles.hh"
  5
  6namespace Rivet {
  7
  8
  9  /// @brief e+e- -> Jpsi K+K-
 10  class BELLE_2014_I1282602 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2014_I1282602);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22      declare(FinalState(), "FS");
 23      declare(UnstableParticles(), "UFS");
 24      book(_nJPsi, 1,1,1);
 25      for (const string& en : _nJPsi.binning().edges<0>()) {
 26        const double end = std::stod(en)*GeV;
 27        if (isCompatibleWithSqrtS(end)) {
 28          _ecms = en;
 29          break;
 30        }
 31      }
 32      if (_ecms.empty())
 33        MSG_ERROR("Beam energy incompatible with analysis.");
 34    }
 35
 36    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 37      for (const Particle &child : p.children()) {
 38	if(child.children().empty()) {
 39	  --nRes[child.pid()];
 40	  --ncount;
 41	}
 42	else
 43	  findChildren(child,nRes,ncount);
 44      }
 45    }
 46
 47
 48    /// Perform the per-event analysis
 49    void analyze(const Event& event) {
 50      const FinalState& fs = apply<FinalState>(event, "FS");
 51      map<long,int> nCount;
 52      int ntotal(0);
 53      for (const Particle& p : fs.particles()) {
 54	nCount[p.pid()] += 1;
 55	++ntotal;
 56      }
 57      const FinalState& ufs = apply<FinalState>(event, "UFS");
 58      for (const Particle& p : ufs.particles()) {
 59	if(p.children().empty()) continue;
 60	// find the j/psi
 61	if(p.pid()==443) {
 62	  map<long,int> nRes = nCount;
 63	  int ncount = ntotal;
 64	  findChildren(p,nRes,ncount);
 65	  // J/psi pi+pi-
 66	  if(ncount!=2) continue;
 67	  bool matched = true;
 68	  for(auto const & val : nRes) {
 69	    if(abs(val.first)==321) {
 70	      if(val.second !=1) {
 71		matched = false;
 72		break;
 73	      }
 74	    }
 75	    else if(val.second!=0) {
 76	      matched = false;
 77	      break;
 78	    }
 79	  }
 80	  if(matched) {
 81	    _nJPsi->fill(_ecms);
 82	    break;
 83	  }
 84	}
 85      }
 86    }
 87
 88
 89    /// Normalise histograms etc., after the run
 90    void finalize() {
 91      scale(_nJPsi, crossSection()/ sumOfWeights() /picobarn);
 92    }
 93
 94    /// @}
 95
 96
 97    /// @name Histograms
 98    /// @{
 99    BinnedHistoPtr<string> _nJPsi;
100    string _ecms;
101    /// @}
102
103
104  };
105
106
107  RIVET_DECLARE_PLUGIN(BELLE_2014_I1282602);
108
109
110}