Rivet analyses

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

namespace Rivet {


  /// @brief BELLE double differential cross section
  class BELLE_2017_I1607562 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2017_I1607562);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      FinalState fs;
      declare(fs,"FS");
      declare(Thrust(fs),"Thrust");
      // histograms
      const vector<double> bins{0.20,0.25,0.30,0.35,0.40,0.45,0.50,0.55,0.60,
                                0.65,0.70,0.75,0.80,0.85,0.90,0.95,1.00};
      for (size_t ip=0; ip<6; ++ip) {
        book(_h_all[ip], bins);
        book(_h_strong[ip], bins);
        for (size_t iy=1; iy < _h_all[ip]->numBins()+1; ++iy) {
          book(_h_all[ip]->bin(iy), 1, ip+1, iy);
          book(_h_strong[ip]->bin(iy), 2, ip+1, iy);
        }
      }
    }

    bool isWeak(const Particle & p) {
      bool weak = false;
      if(p.parents().empty()) return weak;
      Particle parent = p.parents()[0];
      while (!parent.parents().empty()) {
        if(parent.abspid()==411  || parent.abspid()==421  || parent.abspid()==431  ||
           parent.abspid()==4122 || parent.abspid()==4232 || parent.abspid()==4132 ||
           parent.abspid()==4332) {
          weak=true;
          break;
        }
        parent = parent.parents()[0];
      }
      return weak;
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // get thrust and apply cut
      const Thrust thrust = apply<Thrust>(event,"Thrust");
      if(thrust.thrust()<0.8) vetoEvent;
      // get thrust axis
      Vector3 axis = thrust.thrustAxis();
      Particles charged = apply<FinalState>(event,"FS").particles(Cuts::abspid==PID::KPLUS or
                                  Cuts::abspid==PID::PIPLUS);
      for (unsigned int ix=0;ix<charged.size();++ix) {
        double dot1 = axis.dot(charged[ix].momentum().p3());
        bool weak1 = isWeak(charged[ix]);
        if (2.*charged[ix].momentum().t()/sqrtS()<0.1) continue;
        for(unsigned int iy=ix+1;iy<charged.size();++iy) {
          if (2.*charged[iy].momentum().t()/sqrtS()<0.1) continue;
          double dot2 = axis.dot(charged[iy].momentum().p3());
          bool weak2 = isWeak(charged[iy]);
          if (dot1*dot2<0.) continue;
          FourMomentum p = charged[ix].momentum()+charged[iy].momentum();
          double z12 = 2.*p.t()/sqrtS();
          double m12 = p.mass();
          bool strong = !weak1 && !weak2;
          if (charged[ix].pid()==PID::PIPLUS) {
            if (charged[iy].pid()==PID::PIPLUS) {
              _h_all[1]->fill(z12,m12);
              if (strong) _h_strong[1]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::PIMINUS) {
              _h_all[0]->fill(z12,m12);
              if (strong) _h_strong[0]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::KPLUS) {
              _h_all[3]->fill(z12,m12);
              if (strong) _h_strong[3]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::KMINUS) {
              _h_all[2]->fill(z12,m12);
              if (strong) _h_strong[2]->fill(z12,m12);
            }
          }
          else if (charged[ix].pid()==PID::PIMINUS) {
            if (charged[iy].pid()==PID::PIPLUS) {
              _h_all[0]->fill(z12,m12);
              if (strong) _h_strong[0]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::PIMINUS) {
              _h_all[1]->fill(z12,m12);
              if (strong) _h_strong[1]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::KPLUS) {
              _h_all[2]->fill(z12,m12);
              if (strong) _h_strong[2]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::KMINUS) {
              _h_all[3]->fill(z12,m12);
              if (strong) _h_strong[3]->fill(z12,m12);
            }
          }
          else if (charged[ix].pid()==PID::KPLUS) {
            if (charged[iy].pid()==PID::PIPLUS) {
              _h_all[3]->fill(z12,m12);
              if (strong) _h_strong[3]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::PIMINUS) {
              _h_all[2]->fill(z12,m12);
              if (strong) _h_strong[2]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::KPLUS) {
              _h_all[5]->fill(z12,m12);
              if (strong) _h_strong[5]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::KMINUS) {
              _h_all[4]->fill(z12,m12);
              if (strong) _h_strong[4]->fill(z12,m12);
            }
          }
          else if (charged[ix].pid()==PID::KMINUS) {
            if (charged[iy].pid()==PID::PIPLUS) {
              _h_all[2]->fill(z12,m12);
              if (strong) _h_strong[2]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::PIMINUS) {
              _h_all[3]->fill(z12,m12);
              if (strong) _h_strong[3]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::KPLUS) {
              _h_all[4]->fill(z12,m12);
              if (strong) _h_strong[4]->fill(z12,m12);
            }
            else if (charged[iy].pid()==PID::KMINUS) {
              _h_all[5]->fill(z12,m12);
              if (strong) _h_strong[5]->fill(z12,m12);
            }
          }
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // now need width as well
      double fact = crossSection()/nanobarn/sumOfWeights()/0.05;
      scale(_h_all, fact);
      scale(_h_strong, fact);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DGroupPtr _h_all[6], _h_strong[6];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BELLE_2017_I1607562);

}