CMSSW Reference Manual

This new state is then defined at the point of closest approach to the beam line.

TrajectoryStateClosestToBeamLine TrajectoryStateClosestToBeamLineBuilder::operator()	(	const FTS &	originalFTS,
		const reco::BeamSpot &	beamSpot
	)			const

Definition at line 10 of file TrajectoryStateClosestToBeamLineBuilder.cc.

References TwoTrackMinimumDistance::calculate(), FreeTrajectoryState::charge(), FreeTrajectoryState::curvilinearError(), TwoTrackMinimumDistance::firstAngle(), FreeTrajectoryState::hasError(), LogDebug, GlobalTrajectoryParameters::magneticField(), CurvilinearTrajectoryError::matrix(), FreeTrajectoryState::momentum(), FreeTrajectoryState::parameters(), TwoTrackMinimumDistance::pathLength(), PV3DBase< T, PVType, FrameType >::perp(), TwoTrackMinimumDistance::points(), s, StDecayID::status, and PV3DBase< T, PVType, FrameType >::z().

00012 {
00013   TwoTrackMinimumDistance ttmd;
00014   bool status = ttmd.calculate( originalFTS.parameters(), 
00015         GlobalTrajectoryParameters(
00016                 GlobalPoint(beamSpot.position().x(), beamSpot.position().y(), beamSpot.position().z()), 
00017 //              GlobalPoint(0., 0., 0.), 
00018                 GlobalVector(beamSpot.dxdz(), beamSpot.dydz(), 1.), 
00019 //              GlobalVector(0., 0., 1.), 
00020                 0, &(originalFTS.parameters().magneticField()) ) );
00021   if (!status) {
00022     LogDebug  ("TrackingTools/PatternTools")
00023       << "TrajectoryStateClosestToBeamLine: Failure in TTMD when searching for PCA of track to beamline.\n"
00024       << "TrajectoryStateClosestToBeamLine is now invalid.";
00025     return TrajectoryStateClosestToBeamLine();
00026   }
00027 
00028   pair<GlobalPoint, GlobalPoint> points = ttmd.points();
00029 
00030   GlobalPoint xTrack = points.first;
00031   GlobalVector pTrack = GlobalVector ( GlobalVector::Cylindrical(originalFTS.momentum().perp(), ttmd.firstAngle(), originalFTS.momentum().z()) );
00032 
00033   double s =  ttmd.pathLength().first;
00034 
00035   FreeTrajectoryState theFTS;
00036   if (originalFTS.hasError()) {
00037     const AlgebraicSymMatrix55 &errorMatrix = originalFTS.curvilinearError().matrix();
00038     AnalyticalCurvilinearJacobian curvilinJacobian(originalFTS.parameters(), xTrack,
00039                                                    pTrack, s);
00040     const AlgebraicMatrix55 &jacobian = curvilinJacobian.jacobian();
00041     CurvilinearTrajectoryError cte( ROOT::Math::Similarity(jacobian, errorMatrix) );
00042   
00043     theFTS = FreeTrajectoryState(GlobalTrajectoryParameters(xTrack, pTrack, originalFTS.charge(), 
00044                                         &(originalFTS.parameters().magneticField())),
00045                                 cte);
00046   }
00047   else {
00048     theFTS = FreeTrajectoryState(GlobalTrajectoryParameters(xTrack, pTrack, originalFTS.charge(),
00049                                         &(originalFTS.parameters().magneticField())));
00050   }
00051   return TrajectoryStateClosestToBeamLine(theFTS, points.second, beamSpot);
00052 }


Public Types
typedef FreeTrajectoryState	FTS
Public Member Functions
TrajectoryStateClosestToBeamLine	operator() (const FTS &originalFTS, const reco::BeamSpot &beamSpot) const

TrajectoryStateClosestToBeamLineBuilder Class Reference

Public Types

Public Member Functions

Detailed Description

Member Typedef Documentation

Member Function Documentation