TwoBodyDecayMomConstraintProducer.cc

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#include <memory>
 
#include "FWCore/Framework/interface/Frameworkfwd.h"
#include "FWCore/Framework/interface/global/EDProducer.h"
#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Framework/interface/MakerMacros.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/Utilities/interface/InputTag.h"
 
#include "MagneticField/Records/interface/IdealMagneticFieldRecord.h"
 
#include "DataFormats/TrackReco/interface/Track.h"
#include "DataFormats/TrackReco/interface/TrackFwd.h"
 
#include "TrackingTools/PatternTools/interface/TrackConstraintAssociation.h"
 
#include "Alignment/TwoBodyDecay/interface/TwoBodyDecay.h"
#include "Alignment/TwoBodyDecay/interface/TwoBodyDecayModel.h"
#include "Alignment/TwoBodyDecay/interface/TwoBodyDecayFitter.h"
#include "Alignment/TwoBodyDecay/interface/TwoBodyDecayVirtualMeasurement.h"
#include "Alignment/ReferenceTrajectories/interface/TwoBodyDecayTrajectoryState.h"
 
// // debug
// #include <map>
// #include "TH1F.h"
// #include "TFile.h"
// #include "TLorentzVector.h"
// #include "Alignment/TwoBodyDecay/interface/TwoBodyDecayModel.h"
 
class TwoBodyDecayMomConstraintProducer : public edm::global::EDProducer<> {
public:
  explicit TwoBodyDecayMomConstraintProducer(const edm::ParameterSet&);
  ~TwoBodyDecayMomConstraintProducer() override = default;
 
private:
  void produce(edm::StreamID streamid, edm::Event&, const edm::EventSetup&) const override;
 
  std::pair<double, double> momentaAtVertex(const TwoBodyDecay& tbd) const;
 
  std::pair<double, double> momentaAtInnermostSurface(const TwoBodyDecay& tbd,
                                                      const std::vector<reco::TransientTrack>& ttracks,
                                                      const MagneticField* magField) const;
 
  std::pair<bool, TrajectoryStateOnSurface> innermostState(const reco::TransientTrack& ttrack) const;
  bool match(const TrajectoryStateOnSurface& newTsos, const TrajectoryStateOnSurface& oldTsos) const;
 
  const edm::InputTag srcTag_;
  const edm::InputTag bsSrcTag_;
 
  const TwoBodyDecayFitter tbdFitter_;
 
  const double primaryMass_;
  const double primaryWidth_;
  const double secondaryMass_;
 
  const double sigmaPositionCutValue_;
  const double chi2CutValue_;
  const double fixedMomentumError_;
 
  enum MomentumForRefitting { atVertex, atInnermostSurface };
  const MomentumForRefitting momentumForRefitting_;
 
  static MomentumForRefitting momentumForRefittingFromString(std::string momentumForRefittingString);
 
  edm::EDGetTokenT<reco::TrackCollection> trackCollToken_;
  edm::EDGetTokenT<reco::BeamSpot> bsToken_;
 
  //   // debug
  //   std::map<std::string, TH1F*> histos_;
};
 
TwoBodyDecayMomConstraintProducer::TwoBodyDecayMomConstraintProducer(const edm::ParameterSet& iConfig)
    : srcTag_(iConfig.getParameter<edm::InputTag>("src")),
      bsSrcTag_(iConfig.getParameter<edm::InputTag>("beamSpot")),
      tbdFitter_(iConfig),
      primaryMass_(iConfig.getParameter<double>("primaryMass")),
      primaryWidth_(iConfig.getParameter<double>("primaryWidth")),
      secondaryMass_(iConfig.getParameter<double>("secondaryMass")),
      sigmaPositionCutValue_(iConfig.getParameter<double>("sigmaPositionCut")),
      chi2CutValue_(iConfig.getParameter<double>("chi2Cut")),
      fixedMomentumError_(iConfig.getParameter<double>("fixedMomentumError")),
      momentumForRefitting_(momentumForRefittingFromString(iConfig.getParameter<std::string>("momentumForRefitting"))) {
  trackCollToken_ = consumes<reco::TrackCollection>(edm::InputTag(srcTag_));
  bsToken_ = consumes<reco::BeamSpot>(edm::InputTag(bsSrcTag_));
 
  produces<std::vector<MomentumConstraint> >();
  produces<TrackMomConstraintAssociationCollection>();
 
  //   //debug
  //   histos_["deltaEta1"] = new TH1F( "deltaEta1", "deltaEta1", 200, -1., 1. );
  //   histos_["deltaP1"] = new TH1F( "deltaP1", "deltaP1", 200, -50., 50. );
 
  //   histos_["deltaEta2"] = new TH1F( "deltaEta2", "deltaEta2", 200, -1., 1. );
  //   histos_["deltaP2"] = new TH1F( "deltaP2", "deltaP2", 200, -50., 50. );
}
 
void TwoBodyDecayMomConstraintProducer::produce(edm::StreamID streamid,
                                                edm::Event& iEvent,
                                                const edm::EventSetup& iSetup) const {
  using namespace edm;
 
  Handle<reco::TrackCollection> trackColl;
  iEvent.getByToken(trackCollToken_, trackColl);
 
  Handle<reco::BeamSpot> beamSpot;
  iEvent.getByToken(bsToken_, beamSpot);
 
  ESHandle<MagneticField> magField;
  iSetup.get<IdealMagneticFieldRecord>().get(magField);
 
  edm::RefProd<std::vector<MomentumConstraint> > rPairs = iEvent.getRefBeforePut<std::vector<MomentumConstraint> >();
  std::unique_ptr<std::vector<MomentumConstraint> > pairs(new std::vector<MomentumConstraint>);
  std::unique_ptr<TrackMomConstraintAssociationCollection> output(
      new TrackMomConstraintAssociationCollection(trackColl, rPairs));
 
  if (trackColl->size() == 2) {
    TwoBodyDecayVirtualMeasurement vm(primaryMass_, primaryWidth_, secondaryMass_, *beamSpot.product());
 
    std::vector<reco::TransientTrack> ttracks(2);
    ttracks[0] = reco::TransientTrack(reco::TrackRef(trackColl, 0), magField.product());
    ttracks[0].setES(iSetup);
    ttracks[1] = reco::TransientTrack(reco::TrackRef(trackColl, 1), magField.product());
    ttracks[1].setES(iSetup);
 
    TwoBodyDecay tbd = tbdFitter_.estimate(ttracks, vm);
 
    if (!tbd.isValid() or (tbd.chi2() > chi2CutValue_))
      return;
 
    std::pair<double, double> fitMomenta;
    if (momentumForRefitting_ == atVertex) {
      fitMomenta = momentaAtVertex(tbd);
    } else if (momentumForRefitting_ == atInnermostSurface) {
      fitMomenta = momentaAtInnermostSurface(tbd, ttracks, magField.product());
    }  // no other possibility!!!
 
    if ((fitMomenta.first > 0.) and (fitMomenta.second > 0.)) {
      // produce constraint for first track
      MomentumConstraint constraint1(fitMomenta.first, fixedMomentumError_);
      pairs->push_back(constraint1);
      output->insert(reco::TrackRef(trackColl, 0), edm::Ref<std::vector<MomentumConstraint> >(rPairs, 0));
 
      // produce constraint for second track
      MomentumConstraint constraint2(fitMomenta.second, fixedMomentumError_);
      pairs->push_back(constraint2);
      output->insert(reco::TrackRef(trackColl, 1), edm::Ref<std::vector<MomentumConstraint> >(rPairs, 1));
    }
 
    //     // debug
    //     if ( tbd.isValid() and ( fitMomenta.first > 0. ) and ( fitMomenta.second > 0. ) ) {
    //       TwoBodyDecayModel model;
    //       const std::pair< AlgebraicVector, AlgebraicVector > fitMomenta = model.cartesianSecondaryMomenta( tbd );
 
    //       TLorentzVector recoMomentum1( ttracks[0].track().px(), ttracks[0].track().py(), ttracks[0].track().pz(),
    //                  sqrt((ttracks[0].track().p()*ttracks[0].track().p())+0.105658*0.105658) );
    //       TLorentzVector fitMomentum1( fitMomenta.first[0], fitMomenta.first[1], fitMomenta.first[2],
    //                 sqrt( fitMomenta.first.normsq()+0.105658*0.105658) );
    //       histos_["deltaP1"]->Fill( recoMomentum1.P() - fitMomentum1.P() );
    //       histos_["deltaEta1"]->Fill( recoMomentum1.Eta() - fitMomentum1.Eta() );
 
    //       TLorentzVector recoMomentum2( ttracks[1].track().px(), ttracks[1].track().py(), ttracks[1].track().pz(),
    //                  sqrt((ttracks[1].track().p()*ttracks[1].track().p())+0.105658*0.105658) );
    //       TLorentzVector fitMomentum2( fitMomenta.second[0], fitMomenta.second[1], fitMomenta.second[2],
    //                 sqrt( fitMomenta.second.normsq()+0.105658*0.105658) );
    //       histos_["deltaP2"]->Fill( recoMomentum2.P() - fitMomentum2.P() );
    //       histos_["deltaEta2"]->Fill( recoMomentum2.Eta() - fitMomentum2.Eta() );
    //     }
  }
 
  iEvent.put(std::move(pairs));
  iEvent.put(std::move(output));
}
 
std::pair<double, double> TwoBodyDecayMomConstraintProducer::momentaAtVertex(const TwoBodyDecay& tbd) const {
  // construct global trajectory parameters at the starting point
  TwoBodyDecayModel tbdDecayModel(tbd[TwoBodyDecayParameters::mass], secondaryMass_);
  std::pair<AlgebraicVector, AlgebraicVector> secondaryMomenta = tbdDecayModel.cartesianSecondaryMomenta(tbd);
 
  return std::make_pair(secondaryMomenta.first.norm(), secondaryMomenta.second.norm());
}
 
std::pair<double, double> TwoBodyDecayMomConstraintProducer::momentaAtInnermostSurface(
    const TwoBodyDecay& tbd, const std::vector<reco::TransientTrack>& ttracks, const MagneticField* magField) const {
  std::pair<double, double> result = std::make_pair(-1., -1.);
 
  std::pair<bool, TrajectoryStateOnSurface> oldInnermostState1 = innermostState(ttracks[0]);
  std::pair<bool, TrajectoryStateOnSurface> oldInnermostState2 = innermostState(ttracks[1]);
  if (!oldInnermostState1.second.isValid() || !oldInnermostState2.second.isValid())
    return result;
 
  TwoBodyDecayTrajectoryState::TsosContainer trackTsos(oldInnermostState1.second, oldInnermostState2.second);
  TwoBodyDecayTrajectoryState tbdTrajState(trackTsos, tbd, secondaryMass_, magField, true);
  if (!tbdTrajState.isValid())
    return result;
 
  bool match1 = match(tbdTrajState.trajectoryStates(true).first, oldInnermostState1.second);
  bool match2 = match(tbdTrajState.trajectoryStates(true).second, oldInnermostState2.second);
  if (!match1 || !match2)
    return result;
 
  result = std::make_pair(fabs(1. / tbdTrajState.trajectoryStates(true).first.localParameters().qbp()),
                          fabs(1. / tbdTrajState.trajectoryStates(true).second.localParameters().qbp()));
  return result;
}
 
std::pair<bool, TrajectoryStateOnSurface> TwoBodyDecayMomConstraintProducer::innermostState(
    const reco::TransientTrack& ttrack) const {
  double outerR = ttrack.outermostMeasurementState().globalPosition().perp();
  double innerR = ttrack.innermostMeasurementState().globalPosition().perp();
  bool insideOut = (outerR > innerR);
  return std::make_pair(insideOut, insideOut ? ttrack.innermostMeasurementState() : ttrack.outermostMeasurementState());
}
 
bool TwoBodyDecayMomConstraintProducer::match(const TrajectoryStateOnSurface& newTsos,
                                              const TrajectoryStateOnSurface& oldTsos) const {
  LocalPoint lp1 = newTsos.localPosition();
  LocalPoint lp2 = oldTsos.localPosition();
 
  double deltaX = lp1.x() - lp2.x();
  double deltaY = lp1.y() - lp2.y();
 
  return ((fabs(deltaX) < sigmaPositionCutValue_) && (fabs(deltaY) < sigmaPositionCutValue_));
}
 
TwoBodyDecayMomConstraintProducer::MomentumForRefitting
TwoBodyDecayMomConstraintProducer::momentumForRefittingFromString(std::string strMomentumForRefitting) {
  if (strMomentumForRefitting == "atVertex") {
    return atVertex;
  } else if (strMomentumForRefitting == "atInnermostSurface") {
    return atInnermostSurface;
  } else {
    throw cms::Exception("TwoBodyDecayMomConstraintProducer") << "value of config  variable 'momentumForRefitting': "
                                                              << "has to be 'atVertex' or 'atInnermostSurface'";
  }
}
 
//define this as a plug-in
DEFINE_FWK_MODULE(TwoBodyDecayMomConstraintProducer);