trackAssociationChi2.cc

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#include "SimTracker/TrackAssociation/interface/trackAssociationChi2.h"
#include "DataFormats/Math/interface/deltaPhi.h"
#include "TrackingTools/PatternTools/interface/trackingParametersAtClosestApproachToBeamSpot.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"

namespace track_associator {
  constexpr double invalidChi2 = 10000000000.;

  double trackAssociationChi2(const reco::TrackBase::ParameterVector& rParameters,
                              const reco::TrackBase::CovarianceMatrix& recoTrackCovMatrix,
                              const Basic3DVector<double>& momAtVtx,
                              const Basic3DVector<double>& vert,
                              int charge,
                              const MagneticField& magfield,
                              const reco::BeamSpot& bs) {
    
    double chi2 = invalidChi2;
    
    std::pair<bool,reco::TrackBase::ParameterVector> params = reco::trackingParametersAtClosestApproachToBeamSpot(vert, momAtVtx, charge, magfield, bs);
    if (params.first){
      reco::TrackBase::ParameterVector sParameters=params.second;
      
      reco::TrackBase::ParameterVector diffParameters = rParameters - sParameters;
      diffParameters[2] = reco::deltaPhi(diffParameters[2],0.f);
      chi2 = ROOT::Math::Dot(diffParameters * recoTrackCovMatrix, diffParameters);
      chi2 /= 5;
      
      LogDebug("TrackAssociator") << "====NEW RECO TRACK WITH PT=" << sin(rParameters[1])*float(charge)/rParameters[0] << "====\n" 
                                  << "qoverp sim: " << sParameters[0] << "\n" 
                                  << "lambda sim: " << sParameters[1] << "\n" 
                                  << "phi    sim: " << sParameters[2] << "\n" 
                                  << "dxy    sim: " << sParameters[3] << "\n" 
                                  << "dsz    sim: " << sParameters[4] << "\n" 
                                  << ": " /*<< */ << "\n" 
                                  << "qoverp rec: " << rParameters[0] << "\n" 
                                  << "lambda rec: " << rParameters[1] << "\n" 
                                  << "phi    rec: " << rParameters[2] << "\n" 
                                  << "dxy    rec: " << rParameters[3] << "\n" 
                                  << "dsz    rec: " << rParameters[4] << "\n" 
                                  << ": " /*<< */ << "\n" 
                                  << "chi2: " << chi2 << "\n";
      
    }
    return chi2;
  }

  double trackAssociationChi2(const reco::TrackBase::ParameterVector& rParameters,
                              const reco::TrackBase::CovarianceMatrix& recoTrackCovMatrix,
                              const TrackingParticle& trackingParticle,
                              const MagneticField& magfield,
                              const reco::BeamSpot& bs) {
    const int charge = trackingParticle.charge();
    if(charge==0)
      return invalidChi2;

    const auto tpMom = trackingParticle.momentum();
    Basic3DVector<double> momAtVtx(tpMom.x(), tpMom.y(), tpMom.z());
    Basic3DVector<double> vert(trackingParticle.vertex());

    return trackAssociationChi2(rParameters, recoTrackCovMatrix, momAtVtx, vert, charge, magfield, bs);
  }


  double trackAssociationChi2(const reco::TrackBase& track,
                              const TrackingParticle& trackingParticle,
                              const MagneticField& magfield,
                              const reco::BeamSpot& bs) {
    auto cov = track.covariance();
    cov.Invert();

    return trackAssociationChi2(track.parameters(), cov, trackingParticle, magfield, bs);
  }
}