Rivet analyses

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

namespace Rivet {


  /// @brief e+e- -> hadrons near phi
  class CMD2_1995_I406880 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CMD2_1995_I406880);


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

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

      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");
      book(_nKpKm, "TMP/KpKm", refData(1, 1, 1));
      book(_nK0K0, "TMP/K0K0", refData(1, 1, 2));
      book(_n3pi, "TMP/3pi", refData(1, 1, 3));
      book(_numEtaGamma, "TMP/EtaGamma", refData(1, 1, 4));
    }

    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;
      }
      if (ntotal == 2) {
        if (nCount[321] == 1 && nCount[-321] == 1)
          _nKpKm->fill(sqrtS() / MeV);
        else if (nCount[130] == 1 && nCount[310] == 1)
          _nK0K0->fill(sqrtS() / MeV);
      }
      else if (ntotal == 3 && nCount[211] == 1 && nCount[-211] == 1 && nCount[111] == 1)
        _n3pi->fill(sqrtS() / MeV);

      const FinalState& ufs = apply<FinalState>(event, "UFS");
      for (const Particle& p : ufs.particles()) {
        if (p.children().empty()) continue;
        // find the omega
        if (p.pid() == 221) {
          map<long, int> nRes = nCount;
          int ncount = ntotal;
          findChildren(p, nRes, ncount);
          // eta pi+pi-
          if (ncount != 1) continue;
          bool matched = true;
          for (const auto& val : nRes) {
            if (val.first == 22) {
              if (val.second != 1) {
                matched = false;
                break;
              }
            }
            else if (val.second != 0) {
              matched = false;
              break;
            }
          }
          if (matched) _numEtaGamma->fill(sqrtS() / MeV);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double fact = crossSection() / sumOfWeights() / nanobarn;
      Estimate1DPtr mult;
      scale(_nKpKm, fact);
      book(mult, 1, 1, 1);
      barchart(_nKpKm, mult);
      scale(_nK0K0, fact);
      book(mult, 1, 1, 2);
      barchart(_nK0K0, mult);
      scale(_n3pi, fact);
      book(mult, 1, 1, 3);
      barchart(_n3pi, mult);
      scale(_numEtaGamma, fact);
      book(mult, 1, 1, 4);
      barchart(_numEtaGamma, mult);
    }
    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _nKpKm, _nK0K0, _n3pi, _numEtaGamma;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CMD2_1995_I406880);


}