Rivet analyses

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

namespace Rivet {


  /// @brief CMD3 pi+pi-pi0eta cross section
  class CMD3_2017_I1606078 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CMD3_2017_I1606078);


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

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

      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");


      book(_c_all  , 1, 1, 1);
      book(_c_omega, 1, 1, 2);
      book(_c_rho  , 1, 1, 3);
      book(_c_other, 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) {
      // find the final-state particles
      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;
      }
      // find omega/phi + eta
      const FinalState& ufs = apply<FinalState>(event, "UFS");
      bool found = false, foundOmegaPhi = false;
      for (const Particle& p : ufs.particles()) {
    if(p.children().empty()) continue;
    // find the eta
    if(p.pid()!=221) continue;
    map<long,int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p,nRes,ncount);
    // eta pi+pi-pi0
    if(ncount==3) {
      bool matched = true;
      for(auto const & val : nRes) {
        if(abs(val.first)==211 || val.first==111 ) {
          if(val.second !=1) {
        matched = false;
        break;
          }
        }
        else if(val.second!=0) {
          matched = false;
          break;
        }
      }
      if(matched) {
        _c_all->fill(round(sqrtS()/MeV));
        found = true;
      }
    }
    for (const Particle& p2 : ufs.particles()) {
      if(p2.pid()!=223 && p2.pid()!=333) continue;
      map<long,int> nResB = nRes;
      int ncountB = ncount;
      findChildren(p2,nResB,ncountB);
      if(ncountB!=0) continue;
      bool matched2 = true;
      for(auto const & val : nResB) {
        if(val.second!=0) {
          matched2 = false;
          break;
        }
      }
      if(matched2) {
        if(p2.pid()==223)
          _c_omega->fill(round(sqrtS()/MeV));
        foundOmegaPhi=true;
      }
    }
      }
      // find a_0 rho
      bool founda0Rho=false;
      for (const Particle& p : ufs.particles()) {
        if(p.children().empty()) continue;
    // find the rho
    if(p.pid()!=113 && abs(p.pid())!=213)
      continue;
        map<long,int> nRes = nCount;
        int ncount = ntotal;
        findChildren(p,nRes,ncount);
    int a1id(0);
    if(p.pid()==213)
      a1id = 9000211;
    else if(p.pid()==-213)
      a1id =-9000211;
    else
      a1id = 9000111;
    for (const Particle& p2 : ufs.particles()) {
      if(p2.pid()!=a1id) continue;
      map<long,int> nResB = nRes;
      int ncountB = ncount;
      findChildren(p2,nResB,ncountB);
      if(ncountB!=0) continue;
      bool matched = true;
      for(auto const & val : nResB) {
        if(val.second!=0) {
          matched = false;
          break;
        }
      }
      if(matched) {
        _c_rho->fill(round(sqrtS()/MeV));
        founda0Rho=true;
        break;
      }
    }
    if(founda0Rho) break;
      }
      if(found && !foundOmegaPhi && ! founda0Rho)
    _c_other->fill(round(sqrtS()/MeV));
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double fact = crossSection()/nanobarn/sumOfWeights();
      scale(_c_all,   fact);
      scale(_c_omega, fact);
      scale(_c_rho,   fact);
      scale(_c_other, fact);
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<int> _c_all, _c_omega, _c_rho, _c_other;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(CMD3_2017_I1606078);


}