TrajectoryStateAccessor Class Reference

#include <TrajectoryStateAccessor.h>

Public Member Functions
float	inversePtError () const
	TrajectoryStateAccessor (const FreeTrajectoryState &fts)

Private Attributes
const FreeTrajectoryState &	theFts

Detailed Description

Helper class to obtain the uncertainty on specific trajectory parameters.

Definition at line 10 of file TrajectoryStateAccessor.h.

Constructor & Destructor Documentation

TrajectoryStateAccessor()

TrajectoryStateAccessor::TrajectoryStateAccessor ( const FreeTrajectoryState &  fts )

inline

Definition at line 12 of file TrajectoryStateAccessor.h.

: theFts(fts) {}

Member Function Documentation

inversePtError()

float TrajectoryStateAccessor::inversePtError

(

)

const

Definition at line 5 of file TrajectoryStateAccessor.cc.

References alignCSCRings::corr, FreeTrajectoryState::curvilinearError(), CurvilinearTrajectoryError::matrix(), FreeTrajectoryState::momentum(), pfMETCorrectionType0_cfi::par2, PV3DBase< T, PVType, FrameType >::perp2(), mathSSE::sqrt(), theFts, and PV3DBase< T, PVType, FrameType >::z().

Referenced by ThresholdPtTrajectoryFilter::test().

                                                    {
  GlobalVector momentum = theFts.momentum();
  AlgebraicSymMatrix55 const& errMatrix = theFts.curvilinearError().matrix();

  float ptRec2 = momentum.perp2();
  float pzRec = momentum.z();
  float pzRec2 = pzRec * pzRec;
  float CosTheta2 = (pzRec2) / (ptRec2 + pzRec2);
  float SinTheta2 = 1.f - CosTheta2;

  float par2 = CosTheta2 / ptRec2;

  float InvpErr = errMatrix(0, 0);
  float thetaErr = errMatrix(1, 1);
  float corr = errMatrix(0, 1);

  float invPtErr2 = (InvpErr + par2 * thetaErr - 2.f * std::sqrt(par2) * corr) / (SinTheta2);
  return std::sqrt(invPtErr2);
}

Member Data Documentation

theFts

const FreeTrajectoryState& TrajectoryStateAccessor::theFts

private

Definition at line 17 of file TrajectoryStateAccessor.h.

Referenced by inversePtError().