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 gamma gamma -> eta eta
 10  class BELLE_2010_I862260 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2010_I862260);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22      // Initialise and register projections
 23      declare(FinalState(), "FS");
 24      declare(UnstableParticles(), "UFS");
 25      // book histos
 26      if (inRange(sqrtS()/GeV,1.096,4.)) {
 27        book(_sigmaEtaEta[0],"TMP/nEtaPi_1",refData(1, 1, 1));
 28        if (sqrtS()<=2.) book(_sigmaEtaEta[1],"TMP/nEtaPi_2",refData(1, 1, 2));
 29       	double sMin=1.096,sMax=1.12, step=0.04;
 30       	unsigned int ihist=2;
 31       	while (sMin<3.3) {
 32          if (inRange(sqrtS()/GeV, sMin, sMax)) {
 33            break;
 34          }
 35          sMin=sMax;
 36          sMax+=step;
 37          ihist+=1;
 38          if (fuzzyEquals(2.4, sMin)) step=0.1;
 39        }
 40        if (ihist<=43) book(_h_cTheta,ihist,1,1);
 41      }
 42      else {
 43        throw Error("Invalid CMS energy for BELLE_2010_I862260");
 44      }
 45    }
 46
 47    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 48      for (const Particle &child : p.children()) {
 49        if (child.children().empty()) {
 50          nRes[child.pid()]-=1;
 51          --ncount;
 52        }
 53        else {
 54          findChildren(child,nRes,ncount);
 55        }
 56      }
 57    }
 58
 59    /// Perform the per-event analysis
 60    void analyze(const Event& event) {
 61      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
 62      Particles etas=ufs.particles(Cuts::pid==PID::ETA);
 63      if (etas.size()<2) vetoEvent;
 64      const FinalState& fs = apply<FinalState>(event, "FS");
 65      // find the final-state particles
 66      map<long,int> nCount;
 67      int ntotal(0);
 68      for (const Particle& p : fs.particles()) {
 69        nCount[p.pid()] += 1;
 70        ++ntotal;
 71      }
 72      for (unsigned int ix=0;ix<etas.size();++ix) {
 73       	if (etas[ix].children().empty()) continue;
 74       	map<long,int> nRes=nCount;
 75       	int ncount = ntotal;
 76       	findChildren(etas[ix],nRes,ncount);
 77        for (unsigned int iy=ix+1; iy<etas.size(); ++iy) {
 78          if (etas[iy].children().empty()) continue;
 79          map<long,int> nRes2=nRes;
 80          int ncount2 = ncount;
 81          findChildren(etas[iy],nRes2,ncount2);
 82          if (ncount2 !=0 ) continue;
 83          bool matched = true;
 84          for (const auto& val : nRes2) {
 85            if (val.second!=0) {
 86              matched = false;
 87              break;
 88            }
 89          }
 90          if (matched) {
 91            double cTheta = abs(etas[iy].momentum().z()/etas[iy].momentum().p3().mod());
 92            if (cTheta<=0.9) _sigmaEtaEta[0]->fill(sqrtS());
 93            if (_sigmaEtaEta[1]) _sigmaEtaEta[1]->fill(sqrtS());
 94            if (_h_cTheta ) _h_cTheta ->fill(cTheta);
 95            break;
 96          }
 97        }
 98      }
 99    }
100
101
102    /// Normalise histograms etc., after the run
103    void finalize() {
104      const double fact = crossSection()/nanobarn/sumOfWeights();
105      if (_h_cTheta ) scale(_h_cTheta ,fact);
106      for (unsigned int ix=0;ix<2;++ix) {
107        if (!_sigmaEtaEta[ix]) continue;
108        scale(_sigmaEtaEta[ix], fact);
109        Estimate1DPtr tmp;
110        book(tmp, 1, 1, 1+ix);
111        barchart(_sigmaEtaEta[ix],tmp);
112      }
113    }
114    /// @}
115
116
117    /// @name Histograms
118    /// @{
119    Histo1DPtr _sigmaEtaEta[2], _h_cTheta;
120    /// @}
121
122
123  };
124
125
126  RIVET_DECLARE_PLUGIN(BELLE_2010_I862260);
127
128}