Rivet analyses

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

namespace Rivet {


  /// @brief e+e- > Ds(*)+ Ds*()-
  class BABAR_2010_I864027 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2010_I864027);


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

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

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

      // Book histograms
      book(  _c_DpDm, "/TMP/sigma_DpDm"  );
      book( _c_DpDmS, "/TMP/sigma_DpDmS" );
      book(_c_DpSDmS, "/TMP/sigma_DpSDmS");
    }

    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");
      // total hadronic and muonic cross sections
      map<long,int> nCount;
      int ntotal(0);
      for (const Particle& p : fs.particles()) {
        nCount[p.pid()] += 1;
        ++ntotal;
      }
      // unstable charm analysis
      Particles ds = apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==431 or Cuts::abspid==433);
      for(unsigned int ix=0;ix<ds.size();++ix) {
        const Particle& p1 = ds[ix];
    int id1 = abs(p1.pid());
        // check fs
        bool fs = true;
        for (const Particle & child : p1.children()) {
          if(child.pid()==p1.pid()) {
            fs = false;
            break;
          }
        }
        if(!fs) continue;
        // find the children
        map<long,int> nRes = nCount;
        int ncount = ntotal;
        findChildren(p1,nRes,ncount);
        bool matched=false;
        int sign = p1.pid()/id1;
    // loop over the other fs particles
    for(unsigned int iy=ix+1;iy<ds.size();++iy) {
      const Particle& p2 = ds[iy];
      fs = true;
      for (const Particle & child : p2.children()) {
        if(child.pid()==p2.pid()) {
          fs = false;
          break;
        }
      }
      if(!fs) continue;
      if(p2.pid()/abs(p2.pid())==sign) continue;
      int id2 = abs(p2.pid());
      if(!p2.parents().empty() && p2.parents()[0].pid()==p1.pid())
        continue;
      map<long,int> nRes2 = nRes;
      int ncount2 = ncount;
      findChildren(p2,nRes2,ncount2);
      if(ncount2!=0) continue;
      matched=true;
      for(auto const & val : nRes2) {
        if(val.second!=0) {
          matched = false;
          break;
        }
      }
      if(matched) {
        if(id1==431 && id2==431) {
          _c_DpDm->fill();
        }
        else if(id1==433 && id2==433) {
          _c_DpSDmS->fill();
        }
        else if((id1==431 && id2==433) ||
            (id1==433 && id2==431)) {
          _c_DpDmS->fill();
        }
        break;
      }
    }
    if(matched) break;
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double fact = crossSection()/ sumOfWeights()/nanobarn;
      for(unsigned int iy=1;iy<4;++iy) {
    double sigma = 0.0, error = 0.0;
    if(iy==1) {
      sigma = _c_DpDm->val()*fact;
      error = _c_DpDm->err()*fact;
    }
    else if(iy==2) {
      sigma = _c_DpDmS->val()*fact;
      error = _c_DpDmS->err()*fact;
    }
    else if(iy==3) {
      sigma = _c_DpSDmS->val()*fact;
      error = _c_DpSDmS->err()*fact;
    }
        Estimate1DPtr     mult;
        book(mult, 1, 1, iy);
        for (auto& b : mult->bins()) {
          if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
            b.set(sigma, error);
          }
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    CounterPtr _c_DpDm,_c_DpDmS,_c_DpSDmS;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BABAR_2010_I864027);

}