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Rivet analyses reference

BELLE_2015_I1324785

Cross section for $e^+e^-\to \psi(2S)\pi^+\pi^-$ at energies between 4.0 and 5.5 GeV
Experiment: BELLE (KEKB)
Inspire ID: 1324785
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D91 (2015) 112007, 2015
Beams: e+ e-
Beam energies: (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.0, 2.0); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (2.3, 2.3); (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); (2.4, 2.4); (2.4, 2.4); (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); (2.5, 2.5); (2.5, 2.5); (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); (2.6, 2.6); (2.6, 2.6); (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); (2.7, 2.7); (2.7, 2.7); (2.7, 2.7); (2.7, 2.7); (2.7, 2.7); (2.7, 2.7) GeV
Run details:
  • e+e- to hadrons

Measurement of the cross section for $e^+e^-\to \psi(2S)\pi^+\pi^-$ at energies between 4.0 and 5.5 GeV using radiative return by BELLE. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Source code: BELLE_2015_I1324785.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- > psi(2S) pi+pi-
 10  class BELLE_2015_I1324785 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2015_I1324785);
 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(_nPsi2s, 1, 1, 1);
 25      for (const string& en : _nPsi2s.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    /// Perform the per-event analysis
 48    void analyze(const Event& event) {
 49      const FinalState& fs = apply<FinalState>(event, "FS");
 50      map<long,int> nCount;
 51      int ntotal(0);
 52      for (const Particle& p : fs.particles()) {
 53	nCount[p.pid()] += 1;
 54	++ntotal;
 55      }
 56      const FinalState& ufs = apply<FinalState>(event, "UFS");
 57      for (const Particle& p : ufs.particles()) {
 58	if(p.children().empty()) continue;
 59	// find the psi(2S)
 60	if(p.pid()==100443) {
 61	  map<long,int> nRes = nCount;
 62	  int ncount = ntotal;
 63	  findChildren(p,nRes,ncount);
 64	  // omega pi+pi-
 65	  if(ncount!=2) continue;
 66	  bool matched = true;
 67	  for(auto const & val : nRes) {
 68	    if(abs(val.first)==211) {
 69	      if(val.second !=1) {
 70		matched = false;
 71		break;
 72	      }
 73	    }
 74	    else if(val.second!=0) {
 75	      matched = false;
 76	      break;
 77	    }
 78	  }
 79	  if(matched) {
 80	    _nPsi2s->fill(_ecms);
 81	    break;
 82	  }
 83	}
 84      }
 85    }
 86
 87
 88    /// Normalise histograms etc., after the run
 89    void finalize() {
 90      scale(_nPsi2s, crossSection()/ sumOfWeights() /picobarn);
 91    }
 92
 93    /// @}
 94
 95
 96    /// @name Histograms
 97    /// @{
 98    BinnedHistoPtr<string> _nPsi2s;
 99    string _ecms;
100    /// @}
101
102
103  };
104
105
106  RIVET_DECLARE_PLUGIN(BELLE_2015_I1324785);
107
108
109}