/data/refman/pasoursint/CMSSW_6_1_2_SLHC2/src/DQM/Physics/src/TopDQMHelpers.cc

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#include "DQM/Physics/interface/TopDQMHelpers.h"

Calculate::Calculate(int maxNJets, double wMass): 
  failed_(false), maxNJets_(maxNJets), wMass_(wMass), massWBoson_(-1.), massTopQuark_(-1.)
{
}

double
Calculate::massWBoson(const std::vector<reco::Jet>& jets)
{
  if(!failed_&& massWBoson_<0) operator()(jets); return massWBoson_;
}

double 
Calculate::massTopQuark(const std::vector<reco::Jet>& jets) 
{ 
  if(!failed_&& massTopQuark_<0) operator()(jets); return massTopQuark_; 
}

void
Calculate::operator()(const std::vector<reco::Jet>& jets)
{
  if(maxNJets_<0) maxNJets_=jets.size();
  failed_= jets.size()<(unsigned int) maxNJets_;
  if( failed_){ return; }

  // associate those jets with maximum pt of the vectorial 
  // sum to the hadronic decay chain
  double maxPt=-1.;
  std::vector<int> maxPtIndices;
  maxPtIndices.push_back(-1);
  maxPtIndices.push_back(-1);
  maxPtIndices.push_back(-1);
  for(int idx=0; idx<maxNJets_; ++idx){
    for(int jdx=0; jdx<maxNJets_; ++jdx){ if(jdx<=idx) continue;
      for(int kdx=0; kdx<maxNJets_; ++kdx){ if(kdx==idx || kdx==jdx) continue;
        reco::Particle::LorentzVector sum = jets[idx].p4()+jets[jdx].p4()+jets[kdx].p4();
        if( maxPt<0. || maxPt<sum.pt() ){
          maxPt=sum.pt();
          maxPtIndices.clear();
          maxPtIndices.push_back(idx);
          maxPtIndices.push_back(jdx);
          maxPtIndices.push_back(kdx);
        }
      }
    }
  }
  massTopQuark_= (jets[maxPtIndices[0]].p4()+
                  jets[maxPtIndices[1]].p4()+
                  jets[maxPtIndices[2]].p4()).mass();

  // associate those jets that get closest to the W mass
  // with their invariant mass to the W boson
  double wDist =-1.;
  std::vector<int> wMassIndices;
  wMassIndices.push_back(-1);
  wMassIndices.push_back(-1);
  for(unsigned idx=0; idx<maxPtIndices.size(); ++idx){  
    for(unsigned jdx=0; jdx<maxPtIndices.size(); ++jdx){  
      if( jdx==idx || maxPtIndices[idx]>maxPtIndices[jdx] ) continue;
        reco::Particle::LorentzVector sum = jets[maxPtIndices[idx]].p4()+jets[maxPtIndices[jdx]].p4();
        if( wDist<0. || wDist>fabs(sum.mass()-wMass_) ){
          wDist=fabs(sum.mass()-wMass_);
          wMassIndices.clear();
          wMassIndices.push_back(maxPtIndices[idx]);
          wMassIndices.push_back(maxPtIndices[jdx]);
        }
    }
  }
  massWBoson_= (jets[wMassIndices[0]].p4()+
                jets[wMassIndices[1]].p4()).mass();
}