Rivet analyses

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief e+e- > pi+pi-4pi0 and pi+pi-3pi0 eta
  class BABAR_2021_I1938254 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2021_I1938254);


    /// @name Analysis methods
    ///@{

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");
      // Histograms
      for(unsigned int ix=0;ix<5;++ix) {
    book(_num[ix],"TMP/num_"+to_string(ix));
      }
    }

    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
      for( const Particle &child : p.children()) {
    if(child.children().empty()) {
      --nRes[child.pid()];
      --ncount;
    }
    else
      findChildren(child,nRes,ncount);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");

      map<long,int> nCount;
      int ntotal(0);
      for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
      }
      // stable final state
      if(nCount[211]==1 && nCount[-211]==1 && nCount[111]==4)
    _num[0]->fill();
      // intermediate states
      const FinalState& ufs = apply<FinalState>(event, "UFS");
      for (const Particle& p : ufs.particles(Cuts::pid==221 || Cuts::pid==223)) {
    map<long,int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p,nRes,ncount);
    // eta +X
    int idOther;
    if(p.pid()==221) {
      idOther=223;
      bool matched = true;
      for(auto const & val : nRes) {
        if(abs(val.first)==211 || val.first==-211 ) {
          if(val.second !=1) {
        matched = false;
        break;
          }
        }
        else if(val.first==111) {
          // 1 or 3 pi0
          if(val.second !=3 && val.second != 1) {
        matched = false;
        break;
          }
        }
        else if(val.second!=0) {
          matched = false;
          break;
        }
      }
      if(matched) {
        if(nRes[111]==1)
          _num[1]->fill();
        else
          _num[4]->fill();
      }


    }
    // omega+X
    else {
      idOther=221;
      // omega+ 3pi0
      bool matched = true;
      for(auto const & val : nRes) {
        if(abs(val.first)==111) {
          if(val.second !=3) {
        matched = false;
        break;
          }
        }
        else if(val.second!=0) {
          matched = false;
          break;
        }
      }
      if(matched) {
        _num[3]->fill();
      }
    }
    for (const Particle& p2 : ufs.particles(Cuts::pid==idOther)) {
      map<long,int> nResB = nRes;
      int ncountB = ncount;
      findChildren(p2,nResB,ncountB);
      if(ncountB!=0) continue;
      bool matched2 = true;
      for(auto const & val : nResB) {
        if(val.second!=0) {
          matched2 = false;
          break;
        }
      }
      if(matched2) {
        _num[2]->fill();
      }
    }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double fact = crossSection()/nanobarn/sumOfWeights();
      for (unsigned int ix=0;ix<5;++ix) {
        double sigma = _num[ix]->val()*fact;
        double error = _num[ix]->err()*fact;
        Estimate1DPtr  mult;
        book(mult, 1+ix, 1, 1);
        for (auto& b : mult->bins()) {
          if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
            b.set(sigma, error);
          }
        }
      }
    }

    ///@}


    /// @name Histograms
    ///@{
    CounterPtr _num[5];
    ///@}


  };


  RIVET_DECLARE_PLUGIN(BABAR_2021_I1938254);

}