Rivet analyses

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

namespace Rivet {


  /// @brief e+e- > pi+pi-pi0
  class SND_2020_I1809286 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(SND_2020_I1809286);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");
      for (size_t ix = 0; ix < 2; ++ix) {
        book(_sigma_total[ix], 1 + ix, 1, 1);
        for (const string& en : _sigma_total[ix].binning().edges<0>()) {
          double eval = stod(en) * GeV;
          if (isCompatibleWithSqrtS(eval, 5e-3)) {
            _sqs[ix] = en;
            break;
          }
        }
      }
      raiseBeamErrorIf(_sqs[0].empty() && _sqs[1].empty() && !inRange(sqrtS() / GeV, 1.15, 2.));
      for (size_t ix = 0; ix < 3; ++ix) {
        book(_sigma_res[ix], "/TMP/c_res_" + toString(ix), refData(3, 1, 1 + ix));
      }
      book(_h_x[0], 4, 1, 1);
      book(_h_m[0], 4, 1, 3);
      book(_h_x[1], 4, 1, 2);
      book(_h_m[1], 4, 1, 4);
    }

    void findChildren(const Particle& p, map<long, int>& nRes, int& ncount) const {
      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);
      Particle pip, pim;
      for (const Particle& p : fs.particles()) {
        nCount[p.pid()] += 1;
        ++ntotal;
        if (p.pid() == 211)
          pip = p;
        else if (p.pid() == -211)
          pim = p;
      }
      if (ntotal != 3) vetoEvent;
      if (nCount[-211] == 1 && nCount[211] == 1 && nCount[111] == 1) {
        _sigma_total[0]->fill(_sqs[0]);
        _sigma_total[1]->fill(_sqs[1]);
      }
      else
        vetoEvent;
      if (inRange(sqrtS() / GeV, 1.42, 1.48)) {
        _h_x[0]->fill(pip.p() / sqrtS());
        _h_x[0]->fill(pim.p() / sqrtS());
        _h_m[0]->fill((pip.mom() + pim.mom()).mass() / MeV);
      }
      else if (inRange(sqrtS() / GeV, 1.65, 1.68)) {
        _h_x[1]->fill(pip.p() / sqrtS());
        _h_x[1]->fill(pim.p() / sqrtS());
        _h_m[1]->fill((pip.mom() + pim.mom()).mass() / MeV);
      }
      const FinalState& ufs = apply<FinalState>(event, "UFS");
      for (const Particle& p : ufs.particles(Cuts::abspid == 223 || Cuts::abspid == 113 || Cuts::abspid == 213
                                             || Cuts::abspid == 100113 || Cuts::abspid == 100213)) {
        if (p.children().empty()) continue;
        map<long, int> nRes = nCount;
        int ncount = ntotal;
        findChildren(p, nRes, ncount);
        if (ncount != 1) continue;
        int idOther = 211;
        if (p.pid() == 223 || p.pid() == 113 || p.pid() == 100113)
          idOther = 111;
        else if (p.pid() == 213 || p.pid() == 100213)
          idOther = -211;
        bool matched = true;
        for (const auto& val : nRes) {
          if (val.first == idOther) {
            if (val.second != 1) {
              matched = false;
              break;
            }
          }
          else if (val.second != 0) {
            matched = false;
            break;
          }
        }
        if (!matched) continue;
        if (matched) {
          if (p.pid() == 223)
            _sigma_res[2]->fill(sqrtS());
          else if (p.pid() == 213 || p.pid() == 113) {
            _sigma_res[0]->fill(sqrtS());
          }
          else
            _sigma_res[1]->fill(sqrtS());
          break;
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_x, 1.0, false);
      normalize(_h_m, 1.0, false);
      const double fact = crossSection() / nanobarn / sumOfWeights();
      scale(_sigma_total, fact);
      for (size_t ix = 0; ix < 3; ++ix) {
        scale(_sigma_res[ix], fact);
        Estimate1DPtr tmp;
        book(tmp, 3, 1, 1 + ix);
        barchart(_sigma_res[ix], tmp);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    string _sqs[2];
    Histo1DPtr _sigma_res[3];
    Histo1DPtr _h_x[2], _h_m[2];
    BinnedHistoPtr<string> _sigma_total[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(SND_2020_I1809286);
}