Rivet analyses

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

namespace Rivet {


  /// @brief e+ e- > D Dbar
  class CLEOC_2007_I761696 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOC_2007_I761696);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(Cuts::abspid == 411 || Cuts::abspid == 421), "UFS");
      // histograms
      for (unsigned int ix = 0; ix < 3; ++ix) {
        book(_h[ix], 1, 1, 1 + 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()] -= 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& p1 : ufs.particles()) {
        if (p1.pid() < 0) continue;
        map<long, int> nRes = nCount;
        int ncount = ntotal;
        findChildren(p1, nRes, ncount);
        bool matched = false;
        for (const Particle& p2 : ufs.particles()) {
          if (p2.pid() != -p1.pid()) continue;
          map<long, int> nRes2 = nRes;
          int ncount2 = ncount;
          findChildren(p2, nRes2, ncount2);
          if (ncount2 != 0) continue;
          matched = true;
          for (const auto& val : nRes2) {
            if (val.second != 0) {
              matched = false;
              break;
            }
          }
          if (matched) break;
        }
        if (matched) {
          _h[2]->fill(round(sqrtS() / MeV));
          if (p1.abspid() == 421)
            _h[0]->fill(round(sqrtS() / MeV));
          else if (p1.abspid() == 411)
            _h[1]->fill(round(sqrtS() / MeV));
          break;
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_h, crossSection() / sumOfWeights() / nanobarn);
      BinnedEstimatePtr<int> ratio;
      book(ratio, 1, 1, 4);
      divide(_h[1], _h[0], ratio);
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<int> _h[3];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEOC_2007_I761696);

}