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- > phi eta'
 10  class BESIII_2020_I1788734 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2020_I1788734);
 15
 16
 17    /// @name Analysis methods
 18    ///@{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22
 23      // Initialise and register projections
 24      declare(FinalState(), "FS");
 25      declare(UnstableParticles(), "UFS");
 26      book(_nEtaPhi, "TMP/phietaprime");
 27    }
 28
 29    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 30      for (const Particle &child : p.children()) {
 31	if(child.children().empty()) {
 32	  nRes[child.pid()]-=1;
 33	  --ncount;
 34	}
 35	else
 36	  findChildren(child,nRes,ncount);
 37      }
 38    }
 39
 40    /// Perform the per-event analysis
 41    void analyze(const Event& event) {
 42      const FinalState& fs = apply<FinalState>(event, "FS");
 43
 44      map<long,int> nCount;
 45      int ntotal(0);
 46      for (const Particle& p : fs.particles()) {
 47	nCount[p.pid()] += 1;
 48	++ntotal;
 49      }
 50      const FinalState& ufs = apply<FinalState>(event, "UFS");
 51      for (const Particle& p : ufs.particles(Cuts::pid==PID::PHI)) {
 52	if(p.children().empty()) continue;
 53	map<long,int> nRes=nCount;
 54	int ncount = ntotal;
 55	findChildren(p,nRes,ncount);
 56	for (const Particle& p2 : ufs.particles(Cuts::pid==PID::ETAPRIME)) {
 57	  if(p2.parents()[0].isSame(p)) continue;
 58	  map<long,int> nResB = nRes;
 59	  int ncountB = ncount;
 60	  findChildren(p2,nResB,ncountB);
 61	  if(ncountB!=0) continue;
 62	  bool matched2 = true;
 63	  for(auto const & val : nResB) {
 64	    if(val.second!=0) {
 65	      matched2 = false;
 66	      break;
 67	    }
 68	  }
 69	  if(matched2) {
 70	    _nEtaPhi->fill();
 71	  }
 72	}
 73      }
 74    }
 75
 76
 77    /// Normalise histograms etc., after the run
 78    void finalize() {
 79      double sigma = _nEtaPhi->val()*crossSection()/ sumOfWeights() /picobarn;
 80      double error = _nEtaPhi->err()*crossSection()/ sumOfWeights() /picobarn;
 81      Scatter2D temphisto(refData(1, 1, 1));
 82      Scatter2DPtr  mult;
 83      book(mult, 1, 1, 1);
 84      for (size_t b = 0; b < temphisto.numPoints(); b++) {
 85	const double x  = temphisto.point(b).x();
 86	pair<double,double> ex = temphisto.point(b).xErrs();
 87	pair<double,double> ex2 = ex;
 88	if(ex2.first ==0.) ex2. first=0.0001;
 89	if(ex2.second==0.) ex2.second=0.0001;
 90	if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
 91	  mult->addPoint(x, sigma, ex, make_pair(error,error));
 92	}
 93	else {
 94	  mult->addPoint(x, 0., ex, make_pair(0.,.0));
 95	}
 96      }
 97    }
 98
 99    ///@}
100
101
102    /// @name Histograms
103    ///@{
104    CounterPtr _nEtaPhi;
105    ///@}
106
107
108  };
109
110
111  RIVET_DECLARE_PLUGIN(BESIII_2020_I1788734);
112
113}