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- > KK J/Psi
 10  class BESIII_2018_I1653121 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2018_I1653121);
 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(_nKp, "TMP/Kp");
 25      book(_nK0, "TMP/K0");
 26
 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()];
 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      map<long,int> nCount;
 44      int ntotal(0);
 45      for (const Particle& p : fs.particles()) {
 46	nCount[p.pid()] += 1;
 47	++ntotal;
 48      }
 49      const FinalState& ufs = apply<FinalState>(event, "UFS");
 50      for (const Particle& p : ufs.particles()) {
 51	if(p.children().empty()) continue;
 52	// find the J/psi
 53	if(p.pid()==443) {
 54	  map<long,int> nRes = nCount;
 55	  int ncount = ntotal;
 56	  findChildren(p,nRes,ncount);
 57	  // omega pi+pi-
 58	  if(ncount!=2) continue;
 59	  bool matched = true;
 60	  for(auto const & val : nRes) {
 61	    if(abs(val.first)==321 || abs(val.first)==310) {
 62	      continue;
 63	    }
 64	    else if(val.second!=0) {
 65	      matched = false;
 66	      break;
 67	    }
 68	  }
 69	  if(matched) {
 70	    if(nRes[321]==1 && nRes[-321]==1) {
 71	      _nKp->fill();
 72	      break;
 73	    }
 74	    else if(nRes[310]==2) {
 75	      _nK0->fill();
 76	      break;
 77	    }
 78	  }
 79	}
 80      }
 81    }
 82
 83    /// Normalise histograms etc., after the run
 84    void finalize() {
 85      for(unsigned int iy=1;iy<3;++iy) {
 86	double sigma,error;
 87	if(iy==1) {
 88	  sigma = _nKp->val();
 89	  error = _nKp->err();
 90	}
 91	else {
 92	  sigma = _nK0->val();
 93	  error = _nK0->err();
 94	}
 95	sigma *= crossSection()/ sumOfWeights() /picobarn;
 96	error *= crossSection()/ sumOfWeights() /picobarn;
 97	Scatter2D temphisto(refData(1, 1, iy));
 98	Scatter2DPtr  mult;
 99	book(mult, 1, 1, iy);
100	for (size_t b = 0; b < temphisto.numPoints(); b++) {
101	  const double x  = temphisto.point(b).x();
102	  pair<double,double> ex = temphisto.point(b).xErrs();
103	  pair<double,double> ex2 = ex;
104	  if(ex2.first ==0.) ex2. first=0.0001;
105	  if(ex2.second==0.) ex2.second=0.0001;
106	  if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
107	    mult->addPoint(x, sigma, ex, make_pair(error,error));
108	  }
109	  else {
110	    mult->addPoint(x, 0., ex, make_pair(0.,.0));
111	  }
112	}
113      }
114    }
115    //@}
116
117
118    /// @name Histograms
119    //@{
120    CounterPtr _nKp, _nK0;
121    //@}
122
123
124  };
125
126
127  RIVET_DECLARE_PLUGIN(BESIII_2018_I1653121);
128
129}