Acts::FreeTrackParameters Class Reference

Track parameters not bound to a surface for a single track. More...

#include <Acts/EventData/FreeTrackParameters.hpp>

Public Types
using	CovarianceMatrix = FreeMatrix
	Type alias for covariance matrix.
using	ParametersVector = FreeVector
	Type alias for bound parameters vector.

Public Member Functions
	FreeTrackParameters (const FreeVector &params, std::optional< FreeMatrix > cov, ParticleHypothesis particleHypothesis)
	Construct from a parameters vector and particle charge.
	FreeTrackParameters (const Vector4 &pos4, const Vector3 &dir, double qOverP, std::optional< FreeMatrix > cov, ParticleHypothesis particleHypothesis)
	Construct from four-position, direction, absolute momentum, and charge.
	FreeTrackParameters (const Vector4 &pos4, double phi, double theta, double qOverP, std::optional< FreeMatrix > cov, ParticleHypothesis particleHypothesis)
	Construct from four-position, angles, absolute momentum, and charge.
double	absoluteMomentum () const
	Absolute momentum.
double	charge () const
	Particle electric charge.
const std::optional< FreeMatrix > &	covariance () const
	Optional covariance matrix.
Vector3	direction () const
	Unit direction three-vector, i.e.
Vector4	fourPosition () const
	Space-time position four-vector.
template<FreeIndices kIndex>
double	get () const
	Access a single parameter value identified by its index.
Vector3	momentum () const
	Momentum three-vector.
const FreeVector &	parameters () const
	Parameters vector.
const ParticleHypothesis &	particleHypothesis () const
	Particle hypothesis.
double	phi () const
	Phi direction.
Vector3	position () const
	Spatial position three-vector.
double	qOverP () const
	Charge over momentum.
FreeTrackParameters	reflect () const
	Reflect the parameters.
void	reflectInPlace ()
	Reflect the parameters in place.
double	theta () const
	Theta direction.
double	time () const
	Time coordinate.
double	transverseMomentum () const
	Transverse momentum.

Detailed Description

Track parameters not bound to a surface for a single track.

Parameters and covariance matrix are stored using the free parametrization defined in enum FreeIndices.

Constructor & Destructor Documentation

FreeTrackParameters() [1/3]

Acts::FreeTrackParameters::FreeTrackParameters	(	const FreeVector &	params,
		std::optional< FreeMatrix >	cov,
		ParticleHypothesis	particleHypothesis )

Construct from a parameters vector and particle charge.

Parameters

params	Free parameters vector
cov	Free parameters covariance matrix
particleHypothesis	Particle hypothesis

In principle, only the charge magnitude is needed her to allow unambiguous extraction of the absolute momentum. The particle charge is required as an input here to be consistent with the other constructors below that that also take the charge as an input. The charge sign is only used in debug builds to check for consistency with the q/p parameter.

FreeTrackParameters() [2/3]

Acts::FreeTrackParameters::FreeTrackParameters	(	const Vector4 &	pos4,
		const Vector3 &	dir,
		double	qOverP,
		std::optional< FreeMatrix >	cov,
		ParticleHypothesis	particleHypothesis )

Construct from four-position, direction, absolute momentum, and charge.

Parameters

pos4	Track position/time four-vector
dir	Track direction three-vector; normalization is ignored.
qOverP	Charge over momentum
cov	Free parameters covariance matrix
particleHypothesis	Particle hypothesis

FreeTrackParameters() [3/3]

Acts::FreeTrackParameters::FreeTrackParameters	(	const Vector4 &	pos4,
		double	phi,
		double	theta,
		double	qOverP,
		std::optional< FreeMatrix >	cov,
		ParticleHypothesis	particleHypothesis )

Construct from four-position, angles, absolute momentum, and charge.

Parameters

pos4	Track position/time four-vector
phi	Transverse track direction angle
theta	Longitudinal track direction angle
qOverP	Charge over momentum
cov	Free parameters covariance matrix
particleHypothesis	Particle hypothesis

Member Function Documentation

absoluteMomentum()

double Acts::FreeTrackParameters::absoluteMomentum

(

)

const

Absolute momentum.

Returns

The absolute momentum magnitude

charge()

double Acts::FreeTrackParameters::charge

(

)

const

Particle electric charge.

Returns

The particle electric charge

covariance()

const std::optional< FreeMatrix > & Acts::FreeTrackParameters::covariance

(

)

const

Optional covariance matrix.

Returns

Const reference to the optional covariance matrix

direction()

Vector3 Acts::FreeTrackParameters::direction

(

)

const

Unit direction three-vector, i.e.

the normalized momentum three-vector.

Returns

Normalized direction vector

fourPosition()

Vector4 Acts::FreeTrackParameters::fourPosition

(

)

const

Space-time position four-vector.

Returns

Four-dimensional position vector (x, y, z, t)

get()

template<FreeIndices kIndex>

double Acts::FreeTrackParameters::get

(

)

const

Access a single parameter value identified by its index.

Template Parameters

kIndex

Track parameter index

Returns

The parameter value at the specified index

momentum()

Vector3 Acts::FreeTrackParameters::momentum

(

)

const

Momentum three-vector.

Returns

Three-dimensional momentum vector

parameters()

const FreeVector & Acts::FreeTrackParameters::parameters

(

)

const

Parameters vector.

Returns

Const reference to the free parameters vector

particleHypothesis()

const ParticleHypothesis & Acts::FreeTrackParameters::particleHypothesis

(

)

const

Particle hypothesis.

Returns

Reference to the particle hypothesis

phi()

double Acts::FreeTrackParameters::phi

(

)

const

Phi direction.

Returns

The azimuthal angle phi in radians

position()

Vector3 Acts::FreeTrackParameters::position

(

)

const

Spatial position three-vector.

Returns

Three-dimensional position vector (x, y, z)

qOverP()

double Acts::FreeTrackParameters::qOverP

(

)

const

Charge over momentum.

Returns

The charge over momentum ratio

reflect()

FreeTrackParameters Acts::FreeTrackParameters::reflect

(

)

const

Reflect the parameters.

Returns

Reflected parameters.

theta()

double Acts::FreeTrackParameters::theta

(

)

const

Theta direction.

Returns

The polar angle theta in radians

time()

double Acts::FreeTrackParameters::time

(

)

const

Time coordinate.

Returns

The time coordinate value

transverseMomentum()

double Acts::FreeTrackParameters::transverseMomentum

(

)

const

Transverse momentum.

Returns

The transverse momentum magnitude