rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BESIII_2020_I1817739

Cross section for $e^+e^-\to\omega\pi^0$ and $\omega\eta$ for centre-of-mass energies between 2.00 and 3.08 GeV
Experiment: BESIII (BEPC)
Inspire ID: 1817739
Status: VALIDATED
Authors:
  • Peter Richardson
References: Beams: e+ e-
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to\omega\pi^0$ and $\omega\eta$ for centre-of-mass energies between 2.00 and 3.08 GeV by the BESIII collaboration.

Source code: BESIII_2020_I1817739.cc
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief e+e- > omega pi0 and omega eta
  class BESIII_2020_I1817739 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(BESIII_2020_I1817739);


    /// @name Analysis methods
    ///@{

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");
      book(_numOmegaPi, "TMP/OmegaPi");
      book(_nOmegaEta, "/TMP/nOmegaEta");
    }

    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
      for (const Particle &child : p.children()) {
	if(child.children().empty()) {
	  nRes[child.pid()]-=1;
	  --ncount;
	}
	else
	  findChildren(child,nRes,ncount);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");
      map<long,int> nCount;
      int ntotal(0);
      for (const Particle& p : fs.particles()) {
	nCount[p.pid()] += 1;
	++ntotal;
      }
      const FinalState& ufs = apply<FinalState>(event, "UFS");
      for (const Particle& p : ufs.particles(Cuts::pid==223)) {
	if(p.children().empty()) continue;
	map<long,int> nRes = nCount;
	int ncount = ntotal;
	findChildren(p,nRes,ncount);
	// check for omega pi0
	bool matched = true;
	for(auto const & val : nRes) {
	  if(val.first==111) {
	    if(val.second!=1) {
	      matched = false;
	      break;
	    }
	  }
	  else if(val.second!=0) {
	    matched = false;
	    break;
	  }
	}
	if(matched) {
	  _numOmegaPi->fill();
	  break;
	}
	// now for omega eta
	for (const Particle& p2 : ufs.particles(Cuts::pid==221)) {
	  map<long,int> nResB = nRes;
	  int ncountB = ncount;
	  findChildren(p2,nResB,ncountB);
	  if(ncountB!=0) continue;
	  matched = true;
	  for(auto const & val : nResB) {
	    if(val.second!=0) {
	      matched = false;
	      break;
	    }
	  }
	  if(matched) {
	    _nOmegaEta->fill();
	    break;
	  }
	}
	if(matched) break;
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for(unsigned int ix=1;ix<3;++ix) {
	double sigma,error;
	if(ix==1) {
	  sigma = _nOmegaEta->val();
	  error = _nOmegaEta->err();
	}
	else {
	  sigma = _numOmegaPi->val();
	  error = _numOmegaPi->err();
	}
	sigma *= crossSection()/ sumOfWeights() /picobarn;
	error *= crossSection()/ sumOfWeights() /picobarn;
	Scatter2D temphisto(refData(ix, 1, 1));
	Scatter2DPtr mult;
	book(mult, ix, 1, 1);
	for (size_t b = 0; b < temphisto.numPoints(); b++) {
	  const double x  = temphisto.point(b).x();
	  pair<double,double> ex = temphisto.point(b).xErrs();
	  pair<double,double> ex2 = ex;
	  if(ex2.first ==0.) ex2. first=0.0001;
	  if(ex2.second==0.) ex2.second=0.0001;
	  if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
	    mult->addPoint(x, sigma, ex, make_pair(error,error));
	  }
	  else {
	    mult->addPoint(x, 0., ex, make_pair(0.,.0));
	  }
	}
      }
    }

    ///@}


    /// @name Histograms
    ///@{
    CounterPtr _nOmegaEta;
    CounterPtr _numOmegaPi;
    ///@}


  };


  DECLARE_RIVET_PLUGIN(BESIII_2020_I1817739);

}