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- -> pi+ pi- pi0 chi_b1,2
 10  class BELLE_2018_I1678261 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2018_I1678261);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22      // projections
 23      declare(FinalState(), "FS");
 24      declare(UnstableParticles(Cuts::pid==20553 ||	Cuts::pid==555), "UFS");
 25      book(_sigma,1,1,1);
 26      for (const string& en : _sigma.binning().edges<0>()) {
 27        const double end = std::stod(en)*GeV;
 28        if(isCompatibleWithSqrtS(end)) {
 29          _ecms = en;
 30          break;
 31        }
 32      }
 33      if (_ecms.empty()) MSG_ERROR("Beam energy incompatible with analysis.");
 34    }
 35
 36    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 37      for (const Particle &child : p.children()) {
 38        if (child.children().empty()) {
 39          --nRes[child.pid()];
 40          --ncount;
 41        }
 42        else {
 43          findChildren(child,nRes,ncount);
 44        }
 45      }
 46    }
 47
 48    /// Perform the per-event analysis
 49    void analyze(const Event& event) {
 50      const FinalState& fs = apply<FinalState>(event, "FS");
 51      map<long,int> nCount;
 52      int ntotal(0);
 53      for (const Particle& p: fs.particles()) {
 54        nCount[p.pid()] += 1;
 55        ++ntotal;
 56      }
 57      const FinalState& ufs = apply<FinalState>(event, "UFS");
 58      // loop over any chi mesons
 59      for (const Particle& chi : ufs.particles()) {
 60        bool matched = false;
 61        if (chi.children().empty()) continue;
 62        map<long,int> nRes = nCount;
 63        int ncount = ntotal;
 64        findChildren(chi,nRes,ncount);
 65        if (ncount==3) {
 66          matched = true;
 67          for (const auto& val : nRes) {
 68            if (abs(val.first)==PID::PIPLUS || val.first==PID::PI0) {
 69              if (val.second!=1) {
 70                matched = false;
 71                break;
 72              }
 73            }
 74            else if (val.second!=0) {
 75              matched = false;
 76              break;
 77            }
 78          }
 79          if (!matched) continue;
 80          _sigma->fill(_ecms);
 81          break;
 82        }
 83      }
 84    }
 85
 86
 87    /// Normalise histograms etc., after the run
 88    void finalize() {
 89      scale(_sigma, crossSection()/ sumOfWeights() /picobarn);
 90    }
 91
 92    /// @}
 93
 94
 95    /// @name Histograms
 96    /// @{
 97    BinnedHistoPtr<string> _sigma;
 98    string _ecms;
 99    /// @}
100
101
102  };
103
104
105  RIVET_DECLARE_PLUGIN(BELLE_2018_I1678261);
106
107}