LowPtGsfElectronSeedProducer.cc

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// -*- C++ -*-
//
// Package:    ElectronProducers
// Class:      LowPtGsfElectronSeedProducer
//
// Original Author:  Robert Bainbridge

#include "DataFormats/GeometryVector/interface/GlobalPoint.h"
#include "DataFormats/GeometryVector/interface/GlobalVector.h"
#include "DataFormats/Common/interface/ValueMap.h"
#include "DataFormats/Math/interface/deltaPhi.h"
#include "DataFormats/Math/interface/deltaR.h"
#include "DataFormats/Math/interface/LorentzVector.h"
#include "DataFormats/ParticleFlowReco/interface/PFTrajectoryPoint.h"
#include "DataFormats/TrackReco/interface/TrackBase.h"
#include "FastSimulation/BaseParticlePropagator/interface/BaseParticlePropagator.h"
#include "FastSimulation/Particle/interface/RawParticle.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/ParameterSet/interface/ParameterSetDescription.h"
#include "FWCore/Utilities/interface/InputTag.h"
#include "MagneticField/Records/interface/IdealMagneticFieldRecord.h"
#include "RecoEgamma/EgammaElectronProducers/plugins/LowPtGsfElectronSeedProducer.h"
#include "RecoTracker/TransientTrackingRecHit/interface/TkClonerImpl.h"
#include "RecoTracker/TransientTrackingRecHit/interface/TkTransientTrackingRecHitBuilder.h"
#include "TrackingTools/PatternTools/interface/Trajectory.h"
#include "TrackingTools/Records/interface/TransientRecHitRecord.h"
#include "TrackingTools/TrajectoryParametrization/interface/GlobalTrajectoryParameters.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
#include "TMath.h"

//
LowPtGsfElectronSeedProducer::LowPtGsfElectronSeedProducer( const edm::ParameterSet& conf, 
                                const lowptgsfeleseed::HeavyObjectCache* ) :
  field_(),
  fitterPtr_(),
  smootherPtr_(),
  kfTracks_(),
  pfTracks_(),
  ecalClusters_{consumes<reco::PFClusterCollection>(conf.getParameter<edm::InputTag>("ecalClusters"))},
  hcalClusters_(),
  ebRecHits_{consumes<EcalRecHitCollection>(conf.getParameter<edm::InputTag>("EBRecHits"))},
  eeRecHits_{consumes<EcalRecHitCollection>(conf.getParameter<edm::InputTag>("EERecHits"))},
  rho_(consumes<double>(conf.getParameter<edm::InputTag>("rho"))),
  beamSpot_(consumes<reco::BeamSpot>(conf.getParameter<edm::InputTag>("BeamSpot"))),
  fitter_(conf.getParameter<std::string>("Fitter")),
  smoother_(conf.getParameter<std::string>("Smoother")),
  builder_(conf.getParameter<std::string>("TTRHBuilder")),
  passThrough_(conf.getParameter<bool>("PassThrough")),
  usePfTracks_(conf.getParameter<bool>("UsePfTracks")),
  minPtThreshold_(conf.getParameter<double>("MinPtThreshold")),
  maxPtThreshold_(conf.getParameter<double>("MaxPtThreshold"))
{
  if ( usePfTracks_ ) {
    pfTracks_ = consumes<reco::PFRecTrackCollection>(conf.getParameter<edm::InputTag>("pfTracks")); 
    hcalClusters_ = consumes<reco::PFClusterCollection>(conf.getParameter<edm::InputTag>("hcalClusters"));
  }
  kfTracks_ = consumes<reco::TrackCollection>(conf.getParameter<edm::InputTag>("tracks"));

  produces<reco::ElectronSeedCollection>();
  produces<reco::PreIdCollection>();
  produces<reco::PreIdCollection>("HCAL");
  produces< edm::ValueMap<reco::PreIdRef> >(); // indexed by edm::Ref<ElectronSeed>.index()
}

//
LowPtGsfElectronSeedProducer::~LowPtGsfElectronSeedProducer() {}

//
void LowPtGsfElectronSeedProducer::beginLuminosityBlock( edm::LuminosityBlock const&, 
                             edm::EventSetup const& setup ) 
{
  setup.get<IdealMagneticFieldRecord>().get(field_);
}

//
void LowPtGsfElectronSeedProducer::produce( edm::Event& event, 
                        const edm::EventSetup& setup ) 
{
  
  // Products
  auto seeds = std::make_unique<reco::ElectronSeedCollection>();
  auto ecalPreIds = std::make_unique<reco::PreIdCollection>();
  auto hcalPreIds = std::make_unique<reco::PreIdCollection>();

  const edm::RefProd<reco::PreIdCollection> preIdsRefProd =
    event.getRefBeforePut<reco::PreIdCollection>();
  
  // HCAL clusters (only used with PF tracks)
  edm::Handle<reco::PFClusterCollection> hcalClusters;

  //we always need kftracks as we link the preids to them
  edm::Handle<reco::TrackCollection> kfTracks;
  event.getByToken(kfTracks_, kfTracks);

  TrackIndxMap trksToPreIdIndx;
  if ( usePfTracks_ ) { 

    edm::Handle<reco::PFRecTrackCollection> pfTracks;
    event.getByToken(pfTracks_, pfTracks);
    event.getByToken(hcalClusters_,hcalClusters);

    //check consistency between kfTracks and pfTracks collection
    for(auto& trk : *pfTracks){ 
      if(trk.trackRef().isNonnull()){
    if(trk.trackRef().id() != kfTracks.id()){
      throw cms::Exception("ConfigError") << "kfTracks is not the collection that pfTracks was built from, please fix this";
    }
    break; //we only need one valid track ref to check this so end the loop
      }
    }

    loop(pfTracks, // PF tracks
     hcalClusters,
     *seeds,
     *ecalPreIds,
     *hcalPreIds,
     trksToPreIdIndx,
     event,
     setup);

  } else { 

    loop(kfTracks, // KF tracks
     hcalClusters,
     *seeds,
     *ecalPreIds,
     *hcalPreIds,
     trksToPreIdIndx,
     event,
     setup);

  }

  auto ecalPreIdsHandle = event.put(std::move(ecalPreIds));
  event.put(std::move(hcalPreIds),"HCAL");
  event.put(std::move(seeds));

  auto preIdVMOut = std::make_unique< edm::ValueMap<reco::PreIdRef> >();
  edm::ValueMap<reco::PreIdRef>::Filler mapFiller(*preIdVMOut);
  fillPreIdRefValueMap(kfTracks,trksToPreIdIndx,ecalPreIdsHandle,mapFiller);
  mapFiller.fill();
  event.put(std::move(preIdVMOut));
  
}

// Return reco::Track from edm::Ref<T>

reco::TrackRef LowPtGsfElectronSeedProducer::getBaseRef( edm::Handle< std::vector<reco::Track> > handle, int idx ) const 
{
  return reco::TrackRef(handle,idx);
}

reco::TrackRef LowPtGsfElectronSeedProducer::getBaseRef( edm::Handle< std::vector<reco::PFRecTrack> > handle, int idx ) const
{
  return reco::PFRecTrackRef(handle,idx)->trackRef();
}

// Template function, instantiated for both reco::Tracks and reco::PFRecTracks 
template <typename T>
void LowPtGsfElectronSeedProducer::loop( const edm::Handle< std::vector<T> >& handle, // PF or KF tracks
                     edm::Handle<reco::PFClusterCollection>& hcalClusters,
                     reco::ElectronSeedCollection& seeds,
                     reco::PreIdCollection& ecalPreIds, 
                     reco::PreIdCollection& hcalPreIds,
                     TrackIndxMap& trksToPreIdIndx,
                     edm::Event& event,
                     const edm::EventSetup& setup )
{
  
  // Pileup
  edm::Handle<double> rho;
  event.getByToken(rho_,rho);
  
  // Beam spot
  edm::Handle<reco::BeamSpot> spot;
  event.getByToken(beamSpot_,spot);

  // Track fitter
  edm::ESHandle<TrajectoryFitter> fitter;
  setup.get<TrajectoryFitter::Record>().get(fitter_,fitter);
  fitterPtr_ = fitter->clone();

  // Track smoother
  edm::ESHandle<TrajectorySmoother> smoother;
  setup.get<TrajectoryFitter::Record>().get(smoother_,smoother);
  smootherPtr_.reset(smoother->clone());

  // RecHit cloner
  edm::ESHandle<TransientTrackingRecHitBuilder> builder;
  setup.get<TransientRecHitRecord>().get(builder_,builder);
  TkClonerImpl hitCloner = static_cast<TkTransientTrackingRecHitBuilder const*>(builder.product())->cloner();
  fitterPtr_->setHitCloner(&hitCloner);
  smootherPtr_->setHitCloner(&hitCloner);

  // ECAL clusters
  edm::Handle<reco::PFClusterCollection> ecalClusters;
  event.getByToken(ecalClusters_,ecalClusters);

  // Utility to access to shower shape vars
  noZS::EcalClusterLazyTools ecalTools(event,setup,ebRecHits_,eeRecHits_);
  
  // Ensure each cluster is only matched once to a track
  std::vector<int> matchedEcalClusters;
  std::vector<int> matchedHcalClusters;

  // Reserve
  seeds.reserve(handle->size());
  ecalPreIds.reserve(handle->size());
  hcalPreIds.reserve(handle->size());
  
  // Iterate through (PF or KF) tracks
  for ( unsigned int itrk = 0; itrk < handle.product()->size(); itrk++ ) {

    edm::Ref< std::vector<T> > templatedRef(handle,itrk); // TrackRef or PFRecTrackRef
    reco::TrackRef trackRef = getBaseRef(handle,itrk);

    if ( !(trackRef->quality(reco::TrackBase::qualityByName("highPurity"))) ) { continue; }
    if ( !passThrough_ && ( trackRef->pt() < minPtThreshold_ ) ) { continue; }

    // Create ElectronSeed 
    reco::ElectronSeed seed( *(trackRef->seedRef()) );
    seed.setCtfTrack(trackRef);
    
    // Create PreIds
    unsigned int nModels = globalCache()->modelNames().size();
    reco::PreId ecalPreId(nModels);
    reco::PreId hcalPreId(nModels);

    // Add track ref to PreId
    ecalPreId.setTrack(trackRef);
    hcalPreId.setTrack(trackRef);

    // Add Track-Calo matching variables to PreIds
    propagateTrackToCalo(templatedRef,
             ecalClusters,
             hcalClusters,
             matchedEcalClusters,
             matchedHcalClusters,
             ecalPreId,
             hcalPreId );
    
    // Add variables related to GSF tracks to PreId
    lightGsfTracking(ecalPreId,trackRef,seed,setup); 

    // Decision based on BDT 
    bool result = decision(templatedRef,ecalPreId,hcalPreId,*rho,*spot,ecalTools);

    // If fails BDT, do not store seed
    if ( !result ) { continue; }
    
    // Store PreId
    ecalPreIds.push_back(ecalPreId);
    hcalPreIds.push_back(hcalPreId);
    trksToPreIdIndx[trackRef.index()] = ecalPreIds.size()-1;

    // Store ElectronSeed and corresponding edm::Ref<PreId>.index()
    seeds.push_back(seed);

  }

}

// Template instantiation for reco::Tracks
template 
void LowPtGsfElectronSeedProducer::loop<reco::Track>( const edm::Handle< std::vector<reco::Track> >&,
                              edm::Handle<reco::PFClusterCollection>& hcalClusters,
                              reco::ElectronSeedCollection& seeds,
                              reco::PreIdCollection& ecalPreIds, 
                              reco::PreIdCollection& hcalPreIds,
                              TrackIndxMap& trksToPreIdIndx,
                              edm::Event&,
                              const edm::EventSetup& );

// Template instantiation for reco::PFRecTracks
template 
void LowPtGsfElectronSeedProducer::loop<reco::PFRecTrack>( const edm::Handle< std::vector<reco::PFRecTrack> >&,
                               edm::Handle<reco::PFClusterCollection>& hcalClusters,
                               reco::ElectronSeedCollection& seeds,
                               reco::PreIdCollection& ecalPreIds, 
                               reco::PreIdCollection& hcalPreIds,
                               TrackIndxMap& trksToPreIdIndx,
                               edm::Event&,
                               const edm::EventSetup& );

// Loops through both ECAL and HCAL clusters
void LowPtGsfElectronSeedProducer::propagateTrackToCalo( const reco::PFRecTrackRef& pfTrackRef,
                             const edm::Handle<reco::PFClusterCollection>& ecalClusters,
                             const edm::Handle<reco::PFClusterCollection>& hcalClusters,
                             std::vector<int>& matchedEcalClusters,
                             std::vector<int>& matchedHcalClusters,
                             reco::PreId& ecalPreId, 
                             reco::PreId& hcalPreId ) 
{
  propagateTrackToCalo( pfTrackRef, ecalClusters, matchedEcalClusters, ecalPreId, true );
  propagateTrackToCalo( pfTrackRef, hcalClusters, matchedHcalClusters, hcalPreId, false );
}

// Loops through ECAL or HCAL clusters (called twice)
void LowPtGsfElectronSeedProducer::propagateTrackToCalo( const reco::PFRecTrackRef& pfTrackRef,
                             const edm::Handle<reco::PFClusterCollection>& clusters,
                             std::vector<int>& matched,
                             reco::PreId& preId,
                             bool ecal )
{

  // Store info for PreId
  struct Info {
    reco::PFClusterRef cluRef = reco::PFClusterRef();
    float dr2min = 1.e6;
    float deta = 1.e6;
    float dphi = 1.e6;
    math::XYZPoint showerPos = math::XYZPoint(0.,0.,0.);
  } info;
  
  // Find closest "seed cluster" to KF track extrapolated to ECAL (or HCAL)
  reco::PFTrajectoryPoint point;
  if ( ecal ) { point = pfTrackRef->extrapolatedPoint(reco::PFTrajectoryPoint::LayerType::ECALShowerMax); }
  else        { point = pfTrackRef->extrapolatedPoint(reco::PFTrajectoryPoint::LayerType::HCALEntrance); }

  if ( point.isValid() ) {

    Info info;
    for ( unsigned int iclu = 0; iclu < clusters.product()->size(); iclu++ ) {

      if ( std::find( matched.begin(), matched.end(), iclu ) == matched.end() ) {

    reco::PFClusterRef cluRef(clusters,iclu);

    // Determine dR squared
    float dr2 = reco::deltaR2( cluRef->positionREP(), point.positionREP() );

    if ( dr2 < info.dr2min ) {
      info.dr2min = dr2;
      info.cluRef = cluRef;
      info.deta = cluRef->positionREP().eta() - point.positionREP().eta();
      info.dphi = 
        reco::deltaPhi( cluRef->positionREP().phi(), point.positionREP().phi() ) *
        pfTrackRef->trackRef()->charge();
      info.showerPos = point.position();
    }

      }
    }

    // Set PreId content if match found
    if ( info.dr2min < 1.e5 ) { 
      float ep = info.cluRef->correctedEnergy() / std::sqrt( pfTrackRef->trackRef()->innerMomentum().mag2() );
      preId.setECALMatchingProperties( info.cluRef,
                       point.position(), // ECAL or HCAL surface
                       info.showerPos, // 
                       info.deta,
                       info.dphi,
                       0.f, // chieta
                       0.f, // chiphi
                       pfTrackRef->trackRef()->normalizedChi2(), // chi2
                       ep );
    }

  } // clusters

}

// Original implementation in GoodSeedProducer, loops over ECAL clusters only
void LowPtGsfElectronSeedProducer::propagateTrackToCalo( const reco::TrackRef& kfTrackRef,
                             const edm::Handle<reco::PFClusterCollection>& ecalClusters,
                             const edm::Handle<reco::PFClusterCollection>& hcalClusters, // not used
                             std::vector<int>& matchedEcalClusters,
                             std::vector<int>& matchedHcalClusters, // not used
                             reco::PreId& ecalPreId, 
                             reco::PreId& hcalPreId /* not used */ ) 
{

  // Store info for PreId
  struct Info {
    reco::PFClusterRef cluRef = reco::PFClusterRef();
    float dr2min = 1.e6;
    float deta = 1.e6;
    float dphi = 1.e6;
    math::XYZPoint showerPos = math::XYZPoint(0.,0.,0.);
  } info;

  // Propagate 'electron' to ECAL surface
  float energy = sqrt( mass_ + kfTrackRef->outerMomentum().Mag2() );
  XYZTLorentzVector mom = XYZTLorentzVector( kfTrackRef->outerMomentum().x(),
                         kfTrackRef->outerMomentum().y(),
                         kfTrackRef->outerMomentum().z(),
                         energy );
  XYZTLorentzVector pos = XYZTLorentzVector( kfTrackRef->outerPosition().x(),
                         kfTrackRef->outerPosition().y(),
                         kfTrackRef->outerPosition().z(),
                         0. );
  math::XYZVector field(field_->inTesla(GlobalPoint(0,0,0)));
  BaseParticlePropagator particle( RawParticle(mom,pos), 0, 0, field.z() );
  particle.setCharge(kfTrackRef->charge());
  particle.propagateToEcalEntrance(false);
  if ( particle.getSuccess() == 0 ) { return; }
  
  // ECAL entry point for track
  GlobalPoint ecal_pos(particle.vertex().x(),
               particle.vertex().y(),
               particle.vertex().z());

  // Preshower limit
  bool below_ps = pow(ecal_pos.z(),2.) > boundary_*ecal_pos.perp2();
  
  // Iterate through ECAL clusters 
  for ( unsigned int iclu = 0; iclu < ecalClusters.product()->size(); iclu++ ) {
    reco::PFClusterRef cluRef(ecalClusters,iclu);

    // Correct ecal_pos for shower depth 
    double shower_depth = reco::PFCluster::getDepthCorrection(cluRef->correctedEnergy(),
                                  below_ps,
                                  false);
    GlobalPoint showerPos = ecal_pos + 
      GlobalVector(particle.momentum().x(),
           particle.momentum().y(),
           particle.momentum().z()).unit() * shower_depth;

    // Determine dR squared
    float dr2 = reco::deltaR2( cluRef->positionREP(), showerPos );

    // Find nearest ECAL cluster
    if ( dr2 < info.dr2min ) {
      info.dr2min = dr2;
      info.cluRef = cluRef;
      info.deta = std::abs( cluRef->positionREP().eta() - showerPos.eta() );
      info.dphi = 
    std::abs( reco::deltaPhi( cluRef->positionREP().phi(), showerPos.phi() )) * 
    kfTrackRef->charge();
      info.showerPos = showerPos;
    }
  
  }

  // Populate PreId object
  math::XYZPoint point( ecal_pos.x(),
            ecal_pos.y(),
            ecal_pos.z() );

  // Set PreId content
  ecalPreId.setECALMatchingProperties( info.cluRef,
                       point,
                       info.showerPos,
                       info.deta,
                       info.dphi,
                       0.f, // chieta
                       0.f, // chiphi
                       kfTrackRef->normalizedChi2(), // chi2
                       info.cluRef->correctedEnergy() / std::sqrt( kfTrackRef->innerMomentum().mag2() ) ); // E/p

}

// Original implementation for "lightweight" GSF tracking
bool LowPtGsfElectronSeedProducer::lightGsfTracking( reco::PreId& preId,
                             const reco::TrackRef& trackRef,
                             const reco::ElectronSeed& seed,
                             const edm::EventSetup& setup )
{

  Trajectory::ConstRecHitContainer hits;
  for ( unsigned int ihit = 0; ihit < trackRef->recHitsSize(); ++ihit ) {
    hits.push_back( trackRef->recHit(ihit)->cloneSH() );
  }
  
  GlobalVector gv( trackRef->innerMomentum().x(),
           trackRef->innerMomentum().y(),
           trackRef->innerMomentum().z() );
  GlobalPoint gp( trackRef->innerPosition().x(),
          trackRef->innerPosition().y(),
          trackRef->innerPosition().z() );

  GlobalTrajectoryParameters gtps( gp,
                   gv,
                   trackRef->charge(),
                   &*field_ );

  TrajectoryStateOnSurface tsos( gtps,
                 trackRef->innerStateCovariance(),
                 *hits[0]->surface() );

  // Track fitted and smoothed under electron hypothesis
  Trajectory traj1 = fitterPtr_->fitOne( seed, hits, tsos );
  if ( !traj1.isValid() ) { return false; }
  Trajectory traj2 = smootherPtr_->trajectory(traj1);
  if ( !traj2.isValid() ) {  return false; }

  // Set PreId content
  float chi2Ratio = trackRef->chi2() > 0. ? traj2.chiSquared() / trackRef->chi2() : -1.;
  float gsfReducedChi2 = chi2Ratio > -1. ? chi2Ratio * trackRef->normalizedChi2() : -1.;
  float ptOut = traj2.firstMeasurement().updatedState().globalMomentum().perp();
  float ptIn = traj2.lastMeasurement().updatedState().globalMomentum().perp();
  float gsfDpt = ( ptIn > 0 ) ? fabs( ptOut - ptIn ) / ptIn : 0.;
  preId.setTrackProperties(gsfReducedChi2,chi2Ratio,gsfDpt);

  return true;

}

// Decision based on OR of outputs from list of models
bool LowPtGsfElectronSeedProducer::decision( const reco::PFRecTrackRef& pfTrackRef,
                         reco::PreId& ecalPreId,
                         reco::PreId& hcalPreId,
                         double rho,
                         const reco::BeamSpot& spot,
                         noZS::EcalClusterLazyTools& ecalTools )
{
  bool result = false;
  for ( auto& name: globalCache()->modelNames() ) {
    result |= globalCache()->eval(name,
                  ecalPreId,
                  hcalPreId,
                  rho,
                  spot,
                  ecalTools);
  }
  return passThrough_ || ( pfTrackRef->trackRef()->pt() > maxPtThreshold_ ) || result;
}

// 
bool LowPtGsfElectronSeedProducer::decision( const reco::TrackRef& kfTrackRef,
                         reco::PreId& ecalPreId,
                         reco::PreId& hcalPreId,
                         double rho,
                         const reco::BeamSpot& spot,
                         noZS::EcalClusterLazyTools& ecalTools )
{
  // No implementation currently
  return passThrough_;
}
 
template<typename CollType>
void LowPtGsfElectronSeedProducer::fillPreIdRefValueMap( edm::Handle<CollType> tracksHandle,
                             const TrackIndxMap& trksToPreIdIndx,
                             const edm::OrphanHandle<reco::PreIdCollection>& preIdHandle,
                             edm::ValueMap<reco::PreIdRef>::Filler & filler)
{
  std::vector<reco::PreIdRef> values;

  unsigned ntracks=tracksHandle->size();
  for(unsigned itrack=0;itrack<ntracks;++itrack){
    edm::Ref<CollType> trackRef(tracksHandle,itrack);
    auto preIdRefIt = trksToPreIdIndx.find(trackRef.index());
    if(preIdRefIt==trksToPreIdIndx.end()){
      values.push_back(reco::PreIdRef());
    }else{
      edm::Ref<reco::PreIdCollection> preIdRef(preIdHandle,preIdRefIt->second);
      values.push_back(preIdRef);
    }
  }
  filler.insert(tracksHandle,values.begin(),values.end());
}

//
void LowPtGsfElectronSeedProducer::fillDescriptions( edm::ConfigurationDescriptions& descriptions )
{
  edm::ParameterSetDescription desc;
  desc.add<edm::InputTag>("tracks",edm::InputTag("generalTracks"));
  desc.add<edm::InputTag>("pfTracks",edm::InputTag("lowPtGsfElePfTracks"));
  desc.add<edm::InputTag>("ecalClusters",edm::InputTag("particleFlowClusterECAL"));
  desc.add<edm::InputTag>("hcalClusters",edm::InputTag("particleFlowClusterHCAL"));
  desc.add<edm::InputTag>("EBRecHits",edm::InputTag("ecalRecHit","EcalRecHitsEB"));
  desc.add<edm::InputTag>("EERecHits",edm::InputTag("ecalRecHit","EcalRecHitsEE"));
  desc.add<edm::InputTag>("rho",edm::InputTag("fixedGridRhoFastjetAllTmp"));
  desc.add<edm::InputTag>("BeamSpot",edm::InputTag("offlineBeamSpot"));
  desc.add<std::string>("Fitter","GsfTrajectoryFitter_forPreId");
  desc.add<std::string>("Smoother","GsfTrajectorySmoother_forPreId");
  desc.add<std::string>("TTRHBuilder","WithAngleAndTemplate");
  desc.add< std::vector<std::string> >("ModelNames",std::vector<std::string>());
  desc.add< std::vector<std::string> >("ModelWeights",std::vector<std::string>());
  desc.add< std::vector<double> >("ModelThresholds",std::vector<double>());
  desc.add<bool>("PassThrough",false);
  desc.add<bool>("UsePfTracks",true);
  desc.add<double>("MinPtThreshold",1.0);
  desc.add<double>("MaxPtThreshold",15.);
  descriptions.add("lowPtGsfElectronSeeds",desc);
}

//
#include "FWCore/Framework/interface/MakerMacros.h"
DEFINE_FWK_MODULE(LowPtGsfElectronSeedProducer);