SimplePhaseSpace defines a set of static functions to be used for distributing momenta evenly in phase space. More...

Functions
template<typename PType >
void	CMS (Energy2 s, PType &p1, PType &p2)
	Set two momenta in their center of mass system. More...

template<typename PType >
void	CMS (PType &p1, PType &p2, Energy2 s, double cosTheta, double phi)
	Set two momenta in their center of mass system. More...

template<typename PType >
void	CMS (PType &p1, PType &p2, Energy2 s, Energy2 t, double phi, const PType &p0)
	Set two momenta in their center of mass system. More...

template<typename PType >
void	CMS (PType &p1, PType &p2, Energy2 s)
	Set two momenta in their center of mass system. More...

template<typename PPairType >
void	CMS (const PPairType &p, Energy2 s)
	Set two momenta in their center of mass system. More...

template<typename PType >
void	CMS (PType &p1, PType &p2, PType &p3, Energy2 s, double x1, double x3)
	Set three momenta in their center of mass system. More...

template<typename PType >
void	CMS (PType &p1, PType &p2, PType &p3, Energy2 s, double x1, double x3, double phii=0.0, double theta=0.0, double phi=0.0)
	Set three momenta in their center of mass system. More...

Energy	getMagnitude (Energy2 s, Energy m1, Energy m2)
	Calculate the absolute magnitude of the momenta of two particles with masses m1 and m2 when put in their CMS of total invariant mass squared s. More...

Momentum3	polar3Vector (Energy p, double costheta, double phi)
	Calculate the absolute magnitude of the momenta of two particles with masses m1 and m2 when put in their CMS of total invariant mass squared s. More...

vector< LorentzMomentum >	CMSn (Energy m0, const vector< Energy > &m)
	Get a number of randomly distributed momenta. More...

template<typename Container >
void	CMSn (Container &particles, Energy m0)
	Set the momentum of a number of particles. More...

Detailed Description

SimplePhaseSpace defines a set of static functions to be used for distributing momenta evenly in phase space.

In most cases pointers and references to both particle and momentum objects can be used as arguments as long as the ParticleTraits class is specialized properly. When needed, random numbers are generated with the generator given by the static UseRandom class.

Function Documentation

◆ CMS() [1/7]

template<typename PType >

void ThePEG::SimplePhaseSpace::CMS	(	Energy2	s,
		PType &	p1,
		PType &	p2
	)

Set two momenta in their center of mass system.

Their total invariant mass squared is given by s, and their direction is distributed isotropically.

Parameters

s	the total invariant mass squared.
p1	pointer or reference to the first momentum. Its invariant mass will be preserved.
p2	pointer or reference to the second momentum. Its invariant mass will be preserved.

Exceptions

ImpossibleKinematics if the sum of the invariant masses was larger than the given invariant mass ( $\sqrt{s}$ ).

Referenced by CMS().

◆ CMS() [2/7]

template<typename PType >

void ThePEG::SimplePhaseSpace::CMS	(	PType &	p1,
		PType &	p2,
		Energy2	s,
		double	cosTheta,
		double	phi
	)

Set two momenta in their center of mass system.

Their total invariant mass squared is given by s, and their direction is given in terms of the polar and azimuth angle of the first momenta.

Parameters

s	the total invariant mass squared.
p1	pointer or reference to the first momentum. Its invariant mass will be preserved.
p2	pointer or reference to the second momentum. Its invariant mass will be preserved.
cosTheta	cosine of the azimuth angle of the first momentum.
phi	azimuth angle of the first momentum.

Exceptions

ImpossibleKinematics if the sum of the invariant masses was larger than the given invariant mass ( $\sqrt{s}$ ).

◆ CMS() [3/7]

template<typename PType >

void ThePEG::SimplePhaseSpace::CMS	(	PType &	p1,
		PType &	p2,
		Energy2	s,
		Energy2	t,
		double	phi,
		const PType &	p0
	)

Set two momenta in their center of mass system.

Their total invariant mass squared is given by s. The helper momentum p0 is used so that afterwards $t=(p0-p1)^2$ and p1 has the azimuth angle phi around p0.

Parameters

p1	pointer or reference to the first momentum. Its invariant mass will be preserved.
p2	pointer or reference to the second momentum. Its invariant mass will be preserved.
s	the total invariant mass squared.
t	.
phi	azimuth angle of the first momentum around p0.
p0	pointer or reference to an auxiliary momentum.

Exceptions

ImpossibleKinematics if the sum of the invariant masses was larger than the given invariant mass ( $\sqrt{s}$ ).

◆ CMS() [4/7]

template<typename PType >

void ThePEG::SimplePhaseSpace::CMS	(	PType &	p1,
		PType &	p2,
		Energy2	s
	)

Set two momenta in their center of mass system.

Their total invariant mass squared is given by s. p1 will be along the z-axis.

Parameters

p1	pointer or reference to the first momentum. Its invariant mass will be preserved.
p2	pointer or reference to the second momentum. Its invariant mass will be preserved.
s	the total invariant mass squared.

Exceptions

ImpossibleKinematics if the sum of the invariant masses was larger than the given invariant mass ( $\sqrt{s}$ ).

◆ CMS() [5/7]

template<typename PPairType >

void ThePEG::SimplePhaseSpace::CMS	(	const PPairType &	p,
		Energy2	s
	)

Set two momenta in their center of mass system.

Their total invariant mass squared is given by s. The first will be along the z-axis.

Parameters

p	a pair of pointers or references to the two momenta. Their invariant masses will be preserved.
s	the total invariant mass squared.

Exceptions

ImpossibleKinematics if the sum of the invariant masses was larger than the given invariant mass ( $\sqrt{s}$ ).

Definition at line 113 of file SimplePhaseSpace.h.

References CMS(), and getMagnitude().

◆ CMS() [6/7]

template<typename PType >

void ThePEG::SimplePhaseSpace::CMS	(	PType &	p1,
		PType &	p2,
		PType &	p3,
		Energy2	s,
		double	x1,
		double	x3
	)

Set three momenta in their center of mass system.

Their total invariant mass squared is given by s. The energy fraction of particle p1(3) is x1(3) of the total energy and the angles of the system is distributed isotropically.

Parameters

p1	pointer or reference to the first momentum. Its invariant mass will be preserved.
p2	pointer or reference to the second momentum. Its invariant mass will be preserved.
p3	pointer or reference to the second momentum. Its invariant mass will be preserved.
s	the total invariant mass squared.
x1	the energy fraction $2e_1/\sqrt{s}$ .
x3	the energy fraction $2e_3/\sqrt{s}$ .

Exceptions

ImpossibleKinematics if the sum of the invariant masses was larger than the given invariant mass ( $\sqrt{s}$ ).

◆ CMS() [7/7]

template<typename PType >

void ThePEG::SimplePhaseSpace::CMS	(	PType &	p1,
		PType &	p2,
		PType &	p3,
		Energy2	s,
		double	x1,
		double	x3,
		double	phii = `0.0`,
		double	theta = `0.0`,
		double	phi = `0.0`
	)

Set three momenta in their center of mass system.

Their total invariant mass squared is given by s. The energy fraction of particle p1(3) is x1(3) of the total energy. Particle p1 is initially placed along the z-axis and particle p2 is given azimuth angle phii. Then the system is then rotated with theta and phi respectively.

Parameters

p1	pointer or reference to the first momentum. Its invariant mass will be preserved.
p2	pointer or reference to the second momentum. Its invariant mass will be preserved.
p3	pointer or reference to the second momentum. Its invariant mass will be preserved.
s	the total invariant mass squared.
x1	the energy fraction $2e_1/\sqrt{s}$ .
x3	the energy fraction $2e_3/\sqrt{s}$ .
phii	the azimuth angle of p2 around p1.
theta	the polar angle of p1.
phi	the azimuth angle of p1.

Exceptions

ImpossibleKinematics if the sum of the invariant masses was larger than the given invariant mass ( $\sqrt{s}$ ).

◆ CMSn() [1/2]

vector<LorentzMomentum> ThePEG::SimplePhaseSpace::CMSn	(	Energy	m0,
		const vector< Energy > &	m
	)

Get a number of randomly distributed momenta.

Given a number specified invariant masses and a total invariant mass m0, return corresponding four-momenta randomly distributed according to phase space.

Parameters

m0	the total invariant mass of the resulting momenta.
m	a vector of invariant masses of the resulting momenta.

Returns: a vector of momenta with the given masses randomly distributed.

Exceptions

ImpossibleKinematics if the sum of the masses was larger than the given invariant mass ( $\sqrt{s}$ ).

Referenced by polar3Vector().

◆ CMSn() [2/2]

template<typename Container >

void ThePEG::SimplePhaseSpace::CMSn	(	Container &	particles,
		Energy	m0
	)

Set the momentum of a number of particles.

Given a number of particles and a total invariant mass m0, distribute their four-momenta randomly according to phase space.

Parameters

particles	a container of particles or pointers to particles. The invariant mass of these particles will not be chaned.
m0	the total invariant mass of the resulting momenta.

Exceptions

ImpossibleKinematics if the sum of the masses was larger than the given invariant mass ( $\sqrt{s}$ ).

◆ getMagnitude()

Energy ThePEG::SimplePhaseSpace::getMagnitude	(	Energy2	s,
		Energy	m1,
		Energy	m2
	)

Calculate the absolute magnitude of the momenta of two particles with masses m1 and m2 when put in their CMS of total invariant mass squared s.

Parameters

s	the total invariant mass squared.
m1	the mass of particle 1.
m2	the mass of particle 2.

Exceptions

ImpossibleKinematics if the sum of the masses was larger than the given invariant mass ( $\sqrt{s}$ ).

Referenced by CMS().

◆ polar3Vector()

Momentum3 ThePEG::SimplePhaseSpace::polar3Vector	(	Energy	p,
		double	costheta,
		double	phi
	)

inline

Calculate the absolute magnitude of the momenta of two particles with masses m1 and m2 when put in their CMS of total invariant mass squared s.

Parameters

s	the total invariant mass squared.
m1	the mass of particle 1.
m2	the mass of particle 2.

Returns: a negative value if the sum of the masses was larger than the given invariant mass ( $\sqrt{s}$ ). Return a three-vector given the absolute momentum, cos(theta) and phi.

Parameters

p	the magnitude of the momentum.
costheta	the cosine of the polar angle.
phi	the azimuth angle.

Definition at line 197 of file SimplePhaseSpace.h.

References CMSn(), and ThePEG::sqr().

Functions

Detailed Description

Function Documentation

◆ CMS() [1/7]

◆ CMS() [2/7]

◆ CMS() [3/7]

◆ CMS() [4/7]

◆ CMS() [5/7]

◆ CMS() [6/7]

◆ CMS() [7/7]

◆ CMSn() [1/2]

◆ CMSn() [2/2]

◆ getMagnitude()

◆ polar3Vector()