Kinematics tools

Event_selection_framework

Kinematic tools are defined in Common/Kinematics package. SCT kinematics classes are based on Eigen3 library. ROOT implementation of vectors and matrices is abandoned intentionally as too slow.

ThreeVector

| ThreeVector.h (contributors: D. Yakovlev, V. Vorobyev)

The ThreeVector class inherits from Eigen::Matrix<ftype, 1, 3>

template <typename ftype = double>
class ThreeVector : public Eigen::Matrix<ftype, 1, 3>

ThreeVector can be initialized in Cartesian or polar coordinates:

ThreeVector v1(x, y, z);
ThreeVector v2 = ThreeVector::fromRPhiCosth(r, phi, costh)

ThreeVecotor API compared with ROOT TVector3 API

Operation	ThreeVector API	TVector3 API
x component	x(), px()	X(), Px()
y component	y(), py()	Y(), Py()
z component	z(), pz()	Z(), Pz()
Transverse momentum	pt()	Pt()
Norm	norm()	Mag()
Squared norm	norm2(), squaredNorm()	Mag2()

--V.S.Vorobev (talk) 21:53, 25 April 2020 (+07)