GsfConstraintAtVertex.cc

Go to the documentation of this file.

#include "TrackingTools/GsfTracking/interface/GsfConstraintAtVertex.h"

#include "FWCore/MessageLogger/interface/MessageLogger.h"

#include "Geometry/Records/interface/TrackerDigiGeometryRecord.h"
#include "MagneticField/Records/interface/IdealMagneticFieldRecord.h"
#include "TrackingTools/GeomPropagators/interface/AnalyticalPropagator.h"
#include "TrackingTools/Records/interface/TrackingComponentsRecord.h"
#include "TrackingTools/TrajectoryState/interface/TrajectoryStateOnSurface.h"
#include "DataFormats/GeometrySurface/interface/Surface.h"
// #include "TrackingTools/GsfTools/interface/GaussianSumUtilities1D.h"
// #include "TrackingTools/GsfTools/interface/MultiGaussianState1D.h"
// #include "TrackingTools/GsfTools/interface/MultiGaussianStateTransform.h"
#include "TrackingTools/GsfTools/interface/GsfPropagatorAdapter.h"
#include "TrackingTools/PatternTools/interface/TransverseImpactPointExtrapolator.h"
#include "TrackingTools/GsfTracking/interface/GsfMultiStateUpdator.h"
#include "DataFormats/GeometryCommonDetAlgo/interface/ErrorFrameTransformer.h"

GsfConstraintAtVertex::GsfConstraintAtVertex(const TrackerGeometry* geometry, const MagneticField* magField)
    : geometry_(geometry),
      magField_(magField),
      gsfPropagator_(AnalyticalPropagator(magField, anyDirection)),
      tipExtrapolator_(gsfPropagator_) {}

TrajectoryStateOnSurface GsfConstraintAtVertex::constrainAtBeamSpot(const reco::GsfTrack& track,
                                                                    const reco::BeamSpot& beamSpot) const {
  //
  // Beamspot (global co-ordinates)
  //
  GlobalPoint bsPosGlobal(beamSpot.x0(), beamSpot.y0(), beamSpot.z0());
  GlobalError bsCovGlobal(beamSpot.rotatedCovariance3D());
  //
  return constrainAtPoint(track, bsPosGlobal, bsCovGlobal);
}

TrajectoryStateOnSurface GsfConstraintAtVertex::constrainAtVertex(const reco::GsfTrack& track,
                                                                  const reco::Vertex& vertex) const {
  //
  // Beamspot (global co-ordinates)
  //
  GlobalPoint vtxPosGlobal(vertex.position().x(), vertex.position().y(), vertex.position().z());
  GlobalError vtxCovGlobal(vertex.covariance());
  //
  return constrainAtPoint(track, vtxPosGlobal, vtxCovGlobal);
}

TrajectoryStateOnSurface GsfConstraintAtVertex::constrainAtPoint(const reco::GsfTrack& track,
                                                                 const GlobalPoint& globalPosition,
                                                                 const GlobalError& globalError) const {
  //
  // Track on TIP plane
  //
  TrajectoryStateOnSurface innerState = multiStateTransformer_.innerStateOnSurface(track, *geometry_, magField_);
  if (!innerState.isValid())
    return TrajectoryStateOnSurface();
  TrajectoryStateOnSurface tipState = tipExtrapolator_.extrapolate(innerState, globalPosition);
  if (!tipState.isValid())
    return TrajectoryStateOnSurface();
  //
  // RecHit from beam spot
  //
  LocalError bsCovLocal = ErrorFrameTransformer().transform(globalError, tipState.surface());
  auto bsHit =
      TRecHit2DPosConstraint::build(tipState.surface().toLocal(globalPosition), bsCovLocal, &tipState.surface());
  //
  // update with constraint
  //
  TrajectoryStateOnSurface updatedState = gsfUpdator_.update(tipState, *bsHit);
  if (!updatedState.isValid()) {
    edm::LogWarning("GsfConstraintAtVertex") << " GSF update with vertex constraint failed";
    return TrajectoryStateOnSurface();
  }

  return updatedState;
}