File indexing completed on 2024-04-06 12:31:41
0001 #include "TrackingTools/TrajectoryState/interface/TrajectoryStateAccessor.h"
0002 #include "TrackingTools/TrajectoryState/interface/FreeTrajectoryState.h"
0003 #include "TrackingTools/TrajectoryParametrization/interface/CurvilinearTrajectoryError.h"
0004
0005 float TrajectoryStateAccessor::inversePtError() const {
0006 GlobalVector momentum = theFts.momentum();
0007 AlgebraicSymMatrix55 const& errMatrix = theFts.curvilinearError().matrix();
0008
0009 float ptRec2 = momentum.perp2();
0010 float pzRec = momentum.z();
0011 float pzRec2 = pzRec * pzRec;
0012 float CosTheta2 = (pzRec2) / (ptRec2 + pzRec2);
0013 float SinTheta2 = 1.f - CosTheta2;
0014
0015 float par2 = CosTheta2 / ptRec2;
0016
0017 float InvpErr = errMatrix(0, 0);
0018 float thetaErr = errMatrix(1, 1);
0019 float corr = errMatrix(0, 1);
0020
0021 float invPtErr2 = (InvpErr + par2 * thetaErr - 2.f * std::sqrt(par2) * corr) / (SinTheta2);
0022 return std::sqrt(invPtErr2);
0023 }
