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 (const auto& 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);


}