Rivet analyses

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

namespace Rivet {


  /// @brief Add a short analysis description here
  class SND_2016_I1471515 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(SND_2016_I1471515);


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

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");
      book(_nOmegaEtaPi, "/TMP/nOmegaEtaPi");
    }

    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
      for (const Particle &child : p.children()) {
    if(child.children().empty()) {
      nRes[child.pid()]-=1;
      --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;
      }
      const FinalState& ufs = apply<FinalState>(event, "UFS");
      for (const Particle& p : ufs.particles()) {
    if(p.children().empty()) continue;
    if(p.pid()!=223) continue;
    map<long,int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p,nRes,ncount);
    for (const Particle& p2 : ufs.particles()) {
      if(p2.pid()!=221) continue;
      map<long,int> nResB = nRes;
      int ncountB = ncount;
      findChildren(p2,nResB,ncountB);
      if(ncountB!=1) continue;
      bool matched2 = true;
      for(auto const & val : nResB) {
        if(val.first==111) {
          if(val.second!=1) {
        matched2 = false;
        break;
          }
        }
        else if(val.second!=0) {
          matched2 = false;
          break;
        }
      }
      if(matched2) {
        _nOmegaEtaPi->fill();
        break;
      }
    }
      }
    }

    /// Normalise histograms etc., after the run
    void finalize() {
      double sigma = _nOmegaEtaPi->val();
      double error = _nOmegaEtaPi->err();
      sigma *= crossSection()/ sumOfWeights() /nanobarn;
      error *= crossSection()/ sumOfWeights() /nanobarn;
      Estimate1DPtr mult;
      book(mult, 1, 1, 6);
      for (auto& b : mult->bins()) {
        if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
          b.set(sigma, error);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    CounterPtr _nOmegaEtaPi;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(SND_2016_I1471515);


}