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BESIII_2021_I1845443

Cross section for $e^+e^-\to p \bar{p} \eta$ and $p \bar{p} \omega$ at energies between 3.773 and 4.600 GeV
Experiment: BESIII (BEPC)
Inspire ID: 1845443
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Rev.D 104 (2021) 9, 092008
Beams: e+ e-
Beam energies: (1.9, 1.9); (1.9, 1.9); (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); (2.1, 2.1); (2.2, 2.2); (2.2, 2.2); (2.3, 2.3) GeV
Run details:
  • e+e- to hadrons

Cross section for $e^+e^-\to p \bar{p} \eta$ and $p \bar{p} \omega$ at energies between 3.773 and 4.600 GeV measured by the BESIII collaboration. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples.

Source code: BESIII_2021_I1845443.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- -> p pbar eta/omega
 10  class BESIII_2021_I1845443 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1845443);
 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      declare(FinalState(), "FS");
 24      declare(UnstableParticles(), "UFS");
 25      book(_nEta,   1,1,1);
 26      book(_nOmega, 2,1,1);
 27      for (const string& en : _nOmega.binning().edges<0>()) {
 28        const double end = std::stod(en)*GeV;
 29        if (isCompatibleWithSqrtS(end)) {
 30          _ecms = en;
 31          break;
 32        }
 33      }
 34      if(_ecms.empty()) MSG_ERROR("Beam energy incompatible with analysis.");
 35    }
 36
 37    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 38      for (const Particle &child : p.children()) {
 39	if(child.children().empty()) {
 40	  nRes[child.pid()]-=1;
 41	  --ncount;
 42	}
 43	else
 44	  findChildren(child,nRes,ncount);
 45      }
 46    }
 47
 48    /// Perform the per-event analysis
 49    void analyze(const Event& event) {
 50      const FinalState& fs = apply<FinalState>(event, "FS");
 51      // total hadronic and muonic cross sections
 52      map<long,int> nCount;
 53      int ntotal(0);
 54      for (const Particle& p : fs.particles()) {
 55	nCount[p.pid()] += 1;
 56	++ntotal;
 57      }
 58      // find the eta/omega
 59      const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
 60      for(const Particle& p : ufs.particles(Cuts::pid==PID::ETA or Cuts::pid==PID::OMEGA)) {
 61	map<long,int> nRes = nCount;
 62	int ncount = ntotal;
 63	findChildren(p,nRes,ncount);
 64	bool matched=true;
 65	for(auto const & val : nRes) {
 66	  if(abs(val.first)==PID::PROTON) {
 67	    if(val.second!=1) {
 68	      matched = false;
 69	      break;
 70	    }
 71	  }
 72	  else if(val.second!=0) {
 73	    matched = false;
 74	    break;
 75	  }
 76	}
 77	if(matched) {
 78	  if(p.pid()==PID::ETA)
 79	    _nEta->fill(_ecms);
 80	  else
 81	    _nOmega->fill(_ecms);
 82	  break;
 83	}
 84      }
 85    }
 86
 87
 88    /// Normalise histograms etc., after the run
 89    void finalize() {
 90      double fact = crossSection()/ sumOfWeights() /picobarn;
 91      scale(_nEta  ,fact);
 92      scale(_nOmega,fact);
 93    }
 94
 95    ///@}
 96
 97
 98    /// @name Histograms
 99    ///@{
100    BinnedHistoPtr<string> _nEta,_nOmega;
101    string _ecms;
102    ///@}
103
104
105  };
106
107
108  RIVET_DECLARE_PLUGIN(BESIII_2021_I1845443);
109
110}