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        Estimate1DPtr  mult;
 98        book(mult, 1, 1, iy);
 99        for (auto& b : mult->bins()) {
100          if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
101            b.set(sigma, error);
102          }
103        }
104      }
105    }
106    /// @}
107
108
109    /// @name Histograms
110    /// @{
111    CounterPtr _nKp, _nK0;
112    /// @}
113
114
115  };
116
117
118  RIVET_DECLARE_PLUGIN(BESIII_2018_I1653121);
119
120}