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- > eta h_c
 10  class BESIII_2017_I1596897 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2017_I1596897);
 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(_nhc, "TMP/h_c");
 25    }
 26
 27    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 28      for (const Particle &child : p.children()) {
 29        if(child.children().empty()) {
 30          --nRes[child.pid()];
 31          --ncount;
 32        }
 33        else
 34          findChildren(child,nRes,ncount);
 35      }
 36    }
 37
 38    /// Perform the per-event analysis
 39    void analyze(const Event& event) {
 40      const FinalState& fs = apply<FinalState>(event, "FS");
 41      map<long,int> nCount;
 42      int ntotal(0);
 43      for (const Particle& p : fs.particles()) {
 44        nCount[p.pid()] += 1;
 45        ++ntotal;
 46      }
 47      const FinalState& ufs = apply<FinalState>(event, "UFS");
 48      // loop over h_c
 49      for (const Particle& hc : ufs.particles(Cuts::pid==10443)) {
 50        if(hc.children().empty()) continue;
 51        map<long,int> nRes = nCount;
 52        int ncount = ntotal;
 53        findChildren(hc,nRes,ncount);
 54        bool matched = false;
 55        // loop over eta
 56        for(const Particle & eta : ufs.particles(Cuts::pid==221)) {
 57          // check eta not child of h_c
 58          Particle parent=eta;
 59          while(!parent.parents().empty()) {
 60            parent=parent.parents()[0];
 61            if(parent.abspid()==10443) break;
 62          }
 63          if(fuzzyEquals(parent.momentum(),hc.momentum())) continue;
 64          map<long,int> nRes2 = nRes;
 65          int ncount2 = ncount;
 66          findChildren(eta,nRes2,ncount2);
 67          if(ncount2!=0) continue;
 68          matched=true;
 69          for(auto const & val : nRes2) {
 70            if(val.second!=0) {
 71              matched = false;
 72              break;
 73            }
 74          }
 75          if(matched) {
 76            _nhc->fill();
 77            break;
 78          }
 79        }
 80        if(matched) break;
 81      }
 82    }
 83
 84
 85    /// Normalise histograms etc., after the run
 86    void finalize() {
 87      double sigma = _nhc->val();
 88      double error = _nhc->err();
 89      sigma *= crossSection()/ sumOfWeights() /picobarn;
 90      error *= crossSection()/ sumOfWeights() /picobarn;
 91      Estimate1DPtr  mult;
 92      book(mult, 1, 1, 1);
 93      for (auto& b : mult->bins()) {
 94        if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
 95          b.set(sigma, error);
 96        }
 97      }
 98    }
 99
100    /// @}
101
102
103    /// @name Histograms
104    /// @{
105    CounterPtr _nhc;
106    /// @}
107
108
109  };
110
111
112  RIVET_DECLARE_PLUGIN(BESIII_2017_I1596897);
113
114}