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 Add a short analysis description here
 10  class BABAR_2018_I1647139 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2018_I1647139);
 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(_numEtaPiPi, "TMP/EtaPiPi");
 27
 28    }
 29
 30
 31    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 32      for (const Particle &child : p.children()) {
 33	if(child.children().empty()) {
 34	  --nRes[child.pid()];
 35	  --ncount;
 36	}
 37	else
 38	  findChildren(child,nRes,ncount);
 39      }
 40    }
 41
 42    /// Perform the per-event analysis
 43    void analyze(const Event& event) {
 44      const FinalState& fs = apply<FinalState>(event, "FS");
 45
 46      map<long,int> nCount;
 47      int ntotal(0);
 48      for (const Particle& p : fs.particles()) {
 49	nCount[p.pid()] += 1;
 50	++ntotal;
 51      }
 52      const FinalState& ufs = apply<FinalState>(event, "UFS");
 53      for (const Particle& p : ufs.particles()) {
 54	if(p.children().empty()) continue;
 55	// find the omega
 56	if(p.pid()==221) {
 57	  map<long,int> nRes = nCount;
 58	  int ncount = ntotal;
 59	  findChildren(p,nRes,ncount);
 60	  // eta pi+pi-
 61	  if(ncount!=2) continue;
 62	  bool matched = true;
 63	  for(auto const & val : nRes) {
 64	    if(abs(val.first)==211) {
 65	      if(val.second !=1) {
 66		matched = false;
 67		break;
 68	      }
 69	    }
 70	    else if(val.second!=0) {
 71	      matched = false;
 72	      break;
 73	    }
 74	  }
 75	  if(matched)
 76	    _numEtaPiPi->fill();
 77	}
 78      }
 79    }
 80
 81
 82    /// Normalise histograms etc., after the run
 83    void finalize() {
 84
 85      double sigma = _numEtaPiPi->val();
 86      double error = _numEtaPiPi->err();
 87      sigma *= crossSection()/ sumOfWeights() /nanobarn;
 88      error *= crossSection()/ sumOfWeights() /nanobarn;
 89      Estimate1DPtr  mult;
 90      book(mult, 1, 1, 1);
 91      for (auto& b : mult->bins()) {
 92        if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
 93          b.set(sigma, error);
 94        }
 95      }
 96    }
 97
 98    /// @}
 99
100
101    /// @name Histograms
102    /// @{
103    CounterPtr _numEtaPiPi;
104    /// @}
105
106
107  };
108
109
110  RIVET_DECLARE_PLUGIN(BABAR_2018_I1647139);
111
112
113}