TauGenJetProducer.cc

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#include "PhysicsTools/JetMCAlgos/plugins/TauGenJetProducer.h"

#include "FWCore/Framework/interface/ESHandle.h"

#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include "FWCore/Utilities/interface/Exception.h"
#include "FWCore/Framework/interface/EventSetup.h"

#include "DataFormats/JetReco/interface/GenJetCollection.h"
#include "DataFormats/JetReco/interface/GenJet.h"
#include "DataFormats/Common/interface/RefToPtr.h"

#include "PhysicsTools/HepMCCandAlgos/interface/GenParticlesHelper.h"

using namespace std;
using namespace edm;
using namespace reco;

TauGenJetProducer::TauGenJetProducer(const edm::ParameterSet& iConfig) :
  inputTagGenParticles_(iConfig.getParameter<InputTag>("GenParticles")),
  tokenGenParticles_(consumes<GenParticleCollection>(inputTagGenParticles_)),
  includeNeutrinos_(iConfig.getParameter<bool>("includeNeutrinos")),
  verbose_(iConfig.getUntrackedParameter<bool>("verbose",false))
{
  

  produces<GenJetCollection>();
}

TauGenJetProducer::~TauGenJetProducer() { }

void TauGenJetProducer::produce(edm::StreamID, Event& iEvent,
                const EventSetup& iSetup) const {

  Handle<GenParticleCollection> genParticles;

  bool found = iEvent.getByToken( tokenGenParticles_, genParticles);

  if ( !found ) {
    std::ostringstream  err;
    err<<" cannot get collection: "
       <<inputTagGenParticles_<<std::endl;
    edm::LogError("TauGenJetProducer")<<err.str();
    throw cms::Exception( "MissingProduct", err.str());
  }

  auto pOutVisTaus = std::make_unique<GenJetCollection>();

  using namespace GenParticlesHelper;

  GenParticleRefVector allStatus2Taus;
  findParticles( *genParticles,
         allStatus2Taus, 15, 2);

  for ( IGR iTau=allStatus2Taus.begin(); iTau!=allStatus2Taus.end(); ++iTau ) {

    // look for all status 1 (stable) descendents
    GenParticleRefVector descendents;
    findDescendents( *iTau, descendents, 1);

    // CV: skip status 2 taus that radiate-off a photon
    //    --> have a status 2 tau lepton in the list of descendents
    GenParticleRefVector status2TauDaughters;
    findDescendents( *iTau, status2TauDaughters, 2, 15 );
    if ( status2TauDaughters.size() > 0 ) continue;

    // loop on descendents, and take all except neutrinos
    math::XYZTLorentzVector sumVisMom;
    Particle::Charge charge = 0;
    Jet::Constituents constituents;

    if(verbose_)
      cout<<"tau "<<(*iTau)<<endl;

    for(IGR igr = descendents.begin();
    igr!= descendents.end(); ++igr ) {

      int absPdgId = abs((*igr)->pdgId());

      // neutrinos
      if(!includeNeutrinos_ ) {
    if( absPdgId == 12 ||
        absPdgId == 14 ||
        absPdgId == 16  )
      continue;
      }

      if(verbose_)
    cout<<"\t"<<(*igr)<<endl;

      charge += (*igr)->charge();
      sumVisMom += (*igr)->p4();

      // need to convert the vector of reference to the constituents
      // to a vector of pointers to build the genjet
      constituents.push_back( refToPtr( *igr) );
    }

    math::XYZPoint vertex;
    GenJet::Specific specific;

    GenJet jet( sumVisMom, vertex, specific, constituents);

    if (charge != (*iTau)->charge() )
      std::cout<<" charge of Tau: " << (*iTau) << " not equal to charge of sum of charge of all descendents. " << std::endl;

    jet.setCharge(charge);
    pOutVisTaus->push_back( jet );

  }
  iEvent.put(std::move(pOutVisTaus) );
}


DEFINE_FWK_MODULE( TauGenJetProducer );