/data/refman/pasoursint/CMSSW_5_3_9_patch3/src/TopQuarkAnalysis/TopJetCombination/plugins/TtSemiLepJetCombWMassDeltaTopMass.cc

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#include "TopQuarkAnalysis/TopJetCombination/plugins/TtSemiLepJetCombWMassDeltaTopMass.h"

#include "AnalysisDataFormats/TopObjects/interface/TtSemiLepEvtPartons.h"
#include "DataFormats/PatCandidates/interface/Electron.h"
#include "DataFormats/PatCandidates/interface/Muon.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "TopQuarkAnalysis/TopTools/interface/MEzCalculator.h"

TtSemiLepJetCombWMassDeltaTopMass::TtSemiLepJetCombWMassDeltaTopMass(const edm::ParameterSet& cfg):
  jets_             (cfg.getParameter<edm::InputTag>("jets"             )),
  leps_             (cfg.getParameter<edm::InputTag>("leps"             )),
  mets_             (cfg.getParameter<edm::InputTag>("mets"             )),
  maxNJets_         (cfg.getParameter<int>          ("maxNJets"         )),
  wMass_            (cfg.getParameter<double>       ("wMass"            )),
  useBTagging_      (cfg.getParameter<bool>         ("useBTagging"      )),
  bTagAlgorithm_    (cfg.getParameter<std::string>  ("bTagAlgorithm"    )),
  minBDiscBJets_    (cfg.getParameter<double>       ("minBDiscBJets"    )),
  maxBDiscLightJets_(cfg.getParameter<double>       ("maxBDiscLightJets")),
  neutrinoSolutionType_(cfg.getParameter<int>       ("neutrinoSolutionType"))
{
  if(maxNJets_<4 && maxNJets_!=-1)
    throw cms::Exception("WrongConfig") 
      << "Parameter maxNJets can not be set to " << maxNJets_ << ". \n"
      << "It has to be larger than 4 or can be set to -1 to take all jets.";

  produces<std::vector<std::vector<int> > >();
  produces<int>("NumberOfConsideredJets");
}

TtSemiLepJetCombWMassDeltaTopMass::~TtSemiLepJetCombWMassDeltaTopMass()
{
}

void
TtSemiLepJetCombWMassDeltaTopMass::produce(edm::Event& evt, const edm::EventSetup& setup)
{
  std::auto_ptr<std::vector<std::vector<int> > > pOut(new std::vector<std::vector<int> >);
  std::auto_ptr<int> pJetsConsidered(new int);

  std::vector<int> match;
  for(unsigned int i = 0; i < 4; ++i) 
    match.push_back( -1 );

  // get jets
  edm::Handle< std::vector<pat::Jet> > jets;
  evt.getByLabel(jets_, jets);

  // get leptons
  edm::Handle< edm::View<reco::RecoCandidate> > leps; 
  evt.getByLabel(leps_, leps);

  // get MET
  edm::Handle< std::vector<pat::MET> > mets;
  evt.getByLabel(mets_, mets);

  // skip events without lepton candidate or less than 4 jets or no MET
  if(leps->empty() || jets->size() < 4 || mets->empty()){
    pOut->push_back( match );
    evt.put(pOut);
    *pJetsConsidered = jets->size();
    evt.put(pJetsConsidered, "NumberOfConsideredJets");
    return;
  }

  unsigned maxNJets = maxNJets_;
  if(maxNJets_ == -1 || (int)jets->size() < maxNJets_) maxNJets = jets->size();
  *pJetsConsidered = maxNJets;
  evt.put(pJetsConsidered, "NumberOfConsideredJets");

  std::vector<bool> isBJet;
  std::vector<bool> isLJet;
  int cntBJets = 0;
  if(useBTagging_) {
    for(unsigned int idx=0; idx<maxNJets; ++idx) {
      isBJet.push_back( ((*jets)[idx].bDiscriminator(bTagAlgorithm_) > minBDiscBJets_    ) );
      isLJet.push_back( ((*jets)[idx].bDiscriminator(bTagAlgorithm_) < maxBDiscLightJets_) );
      if((*jets)[idx].bDiscriminator(bTagAlgorithm_) > minBDiscBJets_    )cntBJets++;
    }
  }

  // -----------------------------------------------------
  // associate those jets that get closest to the W mass
  // with their invariant mass to the hadronic W boson
  // -----------------------------------------------------
  double wDist =-1.;
  std::vector<int> closestToWMassIndices;
  closestToWMassIndices.push_back(-1);
  closestToWMassIndices.push_back(-1);
  for(unsigned idx=0; idx<maxNJets; ++idx){
    if(useBTagging_ && (!isLJet[idx] || (cntBJets<=2 && isBJet[idx]))) continue;
    for(unsigned jdx=(idx+1); jdx<maxNJets; ++jdx){
      if(useBTagging_ && (!isLJet[jdx] || (cntBJets<=2 && isBJet[jdx]) || (cntBJets==3 && isBJet[idx] && isBJet[jdx]))) continue;
      reco::Particle::LorentzVector sum = 
        (*jets)[idx].p4()+
        (*jets)[jdx].p4();
      if( wDist<0. || wDist>fabs(sum.mass()-wMass_) ){
        wDist=fabs(sum.mass()-wMass_);
        closestToWMassIndices.clear();
        closestToWMassIndices.push_back(idx);
        closestToWMassIndices.push_back(jdx);
      }
    }
  }

  // -----------------------------------------------------
  // build a leptonic W boson from the lepton and the MET
  // -----------------------------------------------------
  double neutrino_pz = 0.;
  if(neutrinoSolutionType_!=-1) {
    MEzCalculator mez;
    mez.SetMET( *mets->begin() );
    if( dynamic_cast<const reco::Muon*>(&(leps->front())) )
      mez.SetLepton( (*leps)[0], true );
    else if( dynamic_cast<const reco::GsfElectron*>(&(leps->front())) )
      mez.SetLepton( (*leps)[0], false );
    else
      throw cms::Exception("UnimplementedFeature") << "Type of lepton given together with MET for solving neutrino kinematics is neither muon nor electron.\n";
    neutrino_pz = mez.Calculate(neutrinoSolutionType_);
  }
  const math::XYZTLorentzVector neutrino( mets->begin()->px(), mets->begin()->py(), neutrino_pz, sqrt(mets->begin()->px()*mets->begin()->px()
                                                                                                      + mets->begin()->py()*mets->begin()->py()
                                                                                                      + neutrino_pz*neutrino_pz) );
  const reco::Particle::LorentzVector lepW = neutrino + leps->front().p4();

  // -----------------------------------------------------
  // associate those jets to the hadronic and the leptonic
  // b quark that minimize the difference between
  // hadronic and leptonic top mass
  // -----------------------------------------------------
  double deltaTop=-1.;
  int hadB=-1;
  int lepB=-1;
  if( isValid(closestToWMassIndices[0], jets) && isValid(closestToWMassIndices[1], jets)) {
    const reco::Particle::LorentzVector hadW =
      (*jets)[closestToWMassIndices[0]].p4()+
      (*jets)[closestToWMassIndices[1]].p4();
    // find hadronic b candidate
    for(unsigned idx=0; idx<maxNJets; ++idx){
      if(useBTagging_ && !isBJet[idx]) continue;
      // make sure it's not used up already from the hadronic W
      if( (int)idx!=closestToWMassIndices[0] && (int)idx!=closestToWMassIndices[1] ){
        reco::Particle::LorentzVector hadTop = hadW + (*jets)[idx].p4();
        // find leptonic b candidate
        for(unsigned jdx=0; jdx<maxNJets; ++jdx){
          if(useBTagging_ && !isBJet[jdx]) continue;
          // make sure it's not used up already from the hadronic branch
          if( (int)jdx!=closestToWMassIndices[0] && (int)jdx!=closestToWMassIndices[1] && jdx!=idx ){
            reco::Particle::LorentzVector lepTop = lepW + (*jets)[jdx].p4();
            if( deltaTop<0. || deltaTop>fabs(hadTop.mass()-lepTop.mass()) ){
              deltaTop=fabs(hadTop.mass()-lepTop.mass());
              hadB=idx;
              lepB=jdx;
            }
          }
        }
      }
    }
  }

  match[TtSemiLepEvtPartons::LightQ   ] = closestToWMassIndices[0];
  match[TtSemiLepEvtPartons::LightQBar] = closestToWMassIndices[1];
  match[TtSemiLepEvtPartons::HadB     ] = hadB;
  match[TtSemiLepEvtPartons::LepB     ] = lepB;

  pOut->push_back( match );
  evt.put(pOut);
}