hephysics.vec
Class HepLorentzVector

java.lang.Object
  hephysics.vec.HepLorentzVector

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

LParticle

public class HepLorentzVector
extends Object
implements Serializable

a HepLorentzVector (4-vector) It can hold either space-coordinate and time (x,y,z,t) or 4-momentum (px,py,pz,energy).

See Also:

Serialized Form

Constructor Summary

HepLorentzVector()
Default Lorentz vector constructor

HepLorentzVector(double[] x, double t)
Define a Lorentz vector

HepLorentzVector(double x, double y, double z, double t)
Define a Lorentz vector This can either be (x,y,z,time) or (px,py,pz,energy)

HepLorentzVector(float[] x, double t)
Define a Lorentz vector

HepLorentzVector(Hep3Vector v, double t)
Define Lorentz vector

Method Summary

void	add(HepLorentzVector parent) Add 2 Lorentz vectors
HepLorentzVector	add(HepLorentzVector v, HepLorentzVector w) Add 2 vectors
double	angle(HepLorentzVector momentum) Angle between 2 vectors
void	boost(double bx, double by, double bz) Lorentz Boost using 3-vector
HepLorentzVector	boost(HepLorentzVector fourVector, Hep3Vector boostVector) Boost fourVector with boostVector.
HepLorentzVector	boost(HepLorentzVector fourVector, HepLorentzVector refFourVector) Boost fourVector into system of refFourVector.
Hep3Vector	centerOfMass(List<HepLorentzVector> vecSet) Return a center mass vector
HepLorentzVector	copy() Make exact copy
double	cosTheta() cosTheta
double	dot(HepLorentzVector v, HepLorentzVector w) Dot product
double	e() Get energy
boolean	equals(Object obj) Compre 2 vectors
double	et() Transverse energy.
double	et2() Transverse energy squared.
double	getE() Get energy (as e())
double	getEta() Get a pseudorapidity: eta=-ln (tan (theta/2)) )
double	getT() Get time (as t())
Hep3Vector	getV3() Get 3-vector
int	hashCode() Hash code
double	invariantMass() Same as m().
double	invariantMass2() Same as m2().
boolean	isLightlike(double epsilon) is spacelike?
boolean	isSpacelike() Is particle spacelike (i.e restMass2() smaller than 0)
double	m() Invariant mass.
double	m2() Invariant mass squared
double	mag() Magnitude sqrt(x**2+y**2+z**2)
double	mag2() Magnitude squared: t()*t() - v.mag2() or e()*e() - v.mag2().
double	mt() Transverse mass.
double	mt2() Transverse mass: e()*e() - pz()*pz()
HepLorentzVector	mult(double scalar, HepLorentzVector v) Multiply by a scaler
Hep3Vector	neg(Hep3Vector v)
HepLorentzVector	neg(HepLorentzVector v) Inverse
double	perp() Transverse momentum.
double	perp2() Transverse momentum squared
double	phi() Phi
double	pseudoRapidity() Pseudorapidity.
double	px() Get X position or (Px,Py,Pz)
double	py() Get Y position or Py
double	pz() Get Z position ot Pz
double	rapidity() Rapidity.
double	restMass2() Rest mass squared -- same as m2()
void	setE(double e) Set energy
void	setPx(double px) Set Px
void	setPy(double py) Set Py
void	setPz(double pz) Set Pz
void	setT(double t) Set time
void	setV3(double x, double y, double z) Set 3-vector position or Px,Py,Pz
void	setV3(Hep3Vector v) Set 3-vector
double	skp(HepLorentzVector momentum) Useful: for x1*x2+y1*y2+z1*z2
HepLorentzVector	sub(HepLorentzVector v, HepLorentzVector w) Subtract 2 vectors
double	t() Get time
double	theta() Get theta angle
String	toString() Convert to string
Hep3Vector	v3() Get 3-vector
double	x() Get X position or Px
double	y() Get Y
double	z() Get Z position or Pz

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

HepLorentzVector

public HepLorentzVector()

Default Lorentz vector constructor

HepLorentzVector

public HepLorentzVector(double x,
                        double y,
                        double z,
                        double t)

Define a Lorentz vector This can either be (x,y,z,time) or (px,py,pz,energy)

Parameters:

x - X position (or Px)

y - Y position (or Py)

z - Z position (or Pz)

t - time or energy

HepLorentzVector

public HepLorentzVector(double[] x,
                        double t)

Define a Lorentz vector

Parameters:

x - 3-vector position or momentum

t - time or energy

HepLorentzVector

public HepLorentzVector(float[] x,
                        double t)

Define a Lorentz vector

Parameters:

x - 3-vector with position or 3-momentum

t - time or energy

HepLorentzVector

public HepLorentzVector(Hep3Vector v,
                        double t)

Define Lorentz vector

Parameters:

x - 3-vector with position or 3-momentum

t - time or energy

Method Detail

setV3

public void setV3(Hep3Vector v)

Set 3-vector

Parameters:

v - position 9x,y,z)

setV3

public void setV3(double x,
                  double y,
                  double z)

Set 3-vector position or Px,Py,Pz

Parameters:

x - X

y - Y

z - Z

px

public double px()

Get X position or (Px,Py,Pz)

Returns:

X

py

public double py()

Get Y position or Py

Returns:

Y

pz

public double pz()

Get Z position ot Pz

Returns:

Z

x

public double x()

Get X position or Px

Returns:

X

y

public double y()

Get Y

Returns:

Y

z

public double z()

Get Z position or Pz

Returns:

Z

e

public double e()

Get energy

Returns:

getE

public double getE()

Get energy (as e())

Returns:

setPx

public void setPx(double px)

Set Px

Parameters:

px -

setPy

public void setPy(double py)

Set Py

Parameters:

py -

setPz

public void setPz(double pz)

Set Pz

Parameters:

pz -

add

public void add(HepLorentzVector parent)

Add 2 Lorentz vectors

Parameters:

parent -

mt2

public double mt2()

Transverse mass: e()*e() - pz()*pz()

Returns:

mag2

public double mag2()

Magnitude squared: t()*t() - v.mag2() or e()*e() - v.mag2(). This corresponds to the invariant mass squared

Returns:

boost

public void boost(double bx,
                  double by,
                  double bz)

Lorentz Boost using 3-vector

Parameters:

bx - X

by - Y

bz - Z

setE

public void setE(double e)

Set energy

Parameters:

e - energy

setT

public void setT(double t)

Set time

Parameters:

t - time

t

public double t()

Get time

Returns:

time

getT

public double getT()

Get time (as t())

Returns:

v3

public Hep3Vector v3()

Get 3-vector

Returns:

3-vector

et2

public double et2()

Transverse energy squared.

et

public double et()

Transverse energy.

Returns:

restMass2

public double restMass2()

Rest mass squared -- same as m2()

Returns:

mt

public double mt()

Transverse mass.

Returns:

invariantMass2

public double invariantMass2()

Same as m2().

Returns:

m2

public double m2()

Invariant mass squared

Returns:

t**2 - x**2-y**2-z**2

invariantMass

public double invariantMass()

Same as m(). If m2() is negative then -sqrt(-m2()) is returned.

Returns:

m

public double m()

Invariant mass. If m2() is negative then -sqrt(-m2()) is returned.

Returns:

invariant mass

isSpacelike

public boolean isSpacelike()

Is particle spacelike (i.e restMass2() smaller than 0)

Returns:

true if spacelike

isLightlike

public boolean isLightlike(double epsilon)

is spacelike?

Parameters:

epsilon - precision

Returns:

dot

public double dot(HepLorentzVector v,
                  HepLorentzVector w)

Dot product

Parameters:

v -

w -

Returns:

add

public HepLorentzVector add(HepLorentzVector v,
                            HepLorentzVector w)

Add 2 vectors

Parameters:

v -

w -

Returns:

sub

public HepLorentzVector sub(HepLorentzVector v,
                            HepLorentzVector w)

Subtract 2 vectors

Parameters:

v -

w -

Returns:

mult

public HepLorentzVector mult(double scalar,
                             HepLorentzVector v)

Multiply by a scaler

Parameters:

scalar -

v -

Returns:

neg

public HepLorentzVector neg(HepLorentzVector v)

Inverse

Parameters:

v -

Returns:

neg

public Hep3Vector neg(Hep3Vector v)

centerOfMass

public Hep3Vector centerOfMass(List<HepLorentzVector> vecSet)

Return a center mass vector

Parameters:

vecSet -

Returns:

boost

public HepLorentzVector boost(HepLorentzVector fourVector,
                              Hep3Vector boostVector)

Boost fourVector with boostVector. Note, that beta=abs(boostVector) needs to be 0 < beta < 1.

boost

public HepLorentzVector boost(HepLorentzVector fourVector,
                              HepLorentzVector refFourVector)

Boost fourVector into system of refFourVector.

cosTheta

public double cosTheta()

cosTheta

Returns:

phi

public double phi()

Phi

Returns:

perp

public double perp()

Transverse momentum.

Returns:

pt

perp2

public double perp2()

Transverse momentum squared

Returns:

pt*pt

angle

public double angle(HepLorentzVector momentum)

Angle between 2 vectors

Parameters:

momentum -

Returns:

theta

public double theta()

Get theta angle

Returns:

pseudoRapidity

public double pseudoRapidity()

Pseudorapidity. eta=-ln (tan (theta/2)) )

Returns:

rapidity

public double rapidity()

Rapidity. 0.5*log( (m+z)/(m-z) );

Returns:

getEta

public double getEta()

Get a pseudorapidity: eta=-ln (tan (theta/2)) )

Returns:

pseudorapidity

getV3

public Hep3Vector getV3()

Get 3-vector

Returns:

3-vector

mag

public double mag()

Magnitude sqrt(x**2+y**2+z**2)

Returns:

skp

public double skp(HepLorentzVector momentum)

Useful: for x1*x2+y1*y2+z1*z2

Parameters:

momentum -

Returns:

equals

public boolean equals(Object obj)

Compre 2 vectors

Overrides:

equals in class Object

copy

public HepLorentzVector copy()

Make exact copy

Returns:

new copy

hashCode

public int hashCode()

Hash code

Overrides:

hashCode in class Object

toString

public String toString()

Convert to string

Overrides:

toString in class Object