Contains functions for Monte Carlo generation of decays. More...

Functions
double	ThreeBodym12F2 (double m12, double M, double m1, double m2, double m3)
	Square of the \(m_{12}\) probability density function used in a three-body decay (unnormalized)

double	TernaryThreeBodym12Maximum (double M, double m1, double m2, double m3)
	Determines the maximum of the \(m_{12}\) probability density function used in a three-body decay.

double	GetRandomThreeBodym12 (double M, double m1, double m2, double m3, double fm12max)
	Sample the invariant mass \(m_{12}\) of the leading two daughter particles in a three-body decay.

SimpleParticle	LorentzBoost (const SimpleParticle &part, double vx, double vy, double vz)
	Lorentz boost of the 4-momentum and 4-coordinate of a particle.

SimpleParticle	LorentzBoostMomentumOnly (const SimpleParticle &part, double vx, double vy, double vz)
	Lorentz boost of the 4-momentum of a particle.

SimpleParticle	LorentzBoostMomentaAndCoordinates (const SimpleParticle &part, double vx, double vy, double vz)
	Lorentz boost of the 4-coordinate and 4-momentum of a particle.

std::vector< SimpleParticle >	TwoBodyDecay (const SimpleParticle &Mother, double m1, long long pdg1, double m2, long long pdg2)
	Samples the decay products of a two-body decay.

std::vector< SimpleParticle >	ManyBodyDecay (const SimpleParticle &Mother, std::vector< double > masses, std::vector< long long > pdgs)
	Samples the decay products of a many-body decay.

void	ShuffleDecayProducts (std::vector< double > &masses, std::vector< long long > &pdgs)
	Shuffles the decay products.

double	ParticleDistanceSquared (const SimpleParticle &part1, const SimpleParticle &part2)
	Return the square of the distance between particles at equal time.

double	ComputeDCA (const SimpleParticle &part)
	Computes the distance of closest approach (DCA) to the origin.

Variables
int	threebodysucc = 0
	Used for debugging the succes rate in the rejection sampling of \(m_{12}\).

int	threebodytot = 0

Detailed Description

Contains functions for Monte Carlo generation of decays.

Function Documentation

◆ ComputeDCA()

double thermalfist::ParticleDecaysMC::ComputeDCA ( const SimpleParticle & part )

Computes the distance of closest approach (DCA) to the origin.

Parameters

part Particle

Definition at line 269 of file ParticleDecaysMC.cpp.

◆ GetRandomThreeBodym12()

double thermalfist::ParticleDecaysMC::GetRandomThreeBodym12	(	double	M,
		double	m1,
		double	m2,
		double	m3,
		double	fm12max )

Sample the invariant mass \(m_{12}\) of the leading two daughter particles in a three-body decay.

Parameters

M	Mass of the decaying particle
m1	Mass of the first daughter particle
m2	Mass of the first daughter particle
m3	Mass of the first daughter particle
fm12max	The maximum of the \(m_{12}\) probability density (precomputed with TernaryThreeBodym12Maximum())

Returns: The sampled value of \(m_{12}\)

Definition at line 47 of file ParticleDecaysMC.cpp.

◆ LorentzBoost()

SimpleParticle thermalfist::ParticleDecaysMC::LorentzBoost	(	const SimpleParticle &	part,
		double	vx,
		double	vy,
		double	vz )

Lorentz boost of the 4-momentum and 4-coordinate of a particle.

Parameters

[in]	part	Input particle with a 4-momentum
[in]	vx	Lorentz boost velocity x component
[in]	vy	Lorentz boost velocity y component
[in]	vz	Lorentz boost velocity z component

Returns: SimpleParticle Particle with Lorentz-boosted 4-momentum and 4-coordinate

Definition at line 60 of file ParticleDecaysMC.cpp.

◆ LorentzBoostMomentaAndCoordinates()

SimpleParticle thermalfist::ParticleDecaysMC::LorentzBoostMomentaAndCoordinates	(	const SimpleParticle &	part,
		double	vx,
		double	vy,
		double	vz )

Lorentz boost of the 4-coordinate and 4-momentum of a particle.

Parameters

[in]	part	Input particle with a 4-momentum
[in]	vx	Lorentz boost velocity x component
[in]	vy	Lorentz boost velocity y component
[in]	vz	Lorentz boost velocity z component

Returns: SimpleParticle Particle with Lorentz-boosted 4-momentum

Definition at line 83 of file ParticleDecaysMC.cpp.

◆ LorentzBoostMomentumOnly()

SimpleParticle thermalfist::ParticleDecaysMC::LorentzBoostMomentumOnly	(	const SimpleParticle &	part,
		double	vx,
		double	vy,
		double	vz )

Lorentz boost of the 4-momentum of a particle.

  Does *not* boost the coordinates!

Parameters

[in]	part	Input particle with a 4-momentum
[in]	vx	Lorentz boost velocity x component
[in]	vy	Lorentz boost velocity y component
[in]	vz	Lorentz boost velocity z component

Returns: SimpleParticle Particle with Lorentz-boosted 4-momentum

Definition at line 64 of file ParticleDecaysMC.cpp.

◆ ManyBodyDecay()

std::vector< SimpleParticle > thermalfist::ParticleDecaysMC::ManyBodyDecay	(	const SimpleParticle &	Mother,
		std::vector< double >	masses,
		std::vector< long long >	pdgs )

Samples the decay products of a many-body decay.

NOTE

While the decay kinematics of a three-body decay here are exact, decay kinematics for (4+)-body decays are approximate and should be taken into consideration.

Parameters

Mother	The decaying particle
masses	Masses of the decay products (in GeV)
pdgs	Pdg codes of the decay products

Returns: std::vector<SimpleParticle>

Definition at line 167 of file ParticleDecaysMC.cpp.

◆ ParticleDistanceSquared()

double thermalfist::ParticleDecaysMC::ParticleDistanceSquared	(	const SimpleParticle &	part1,
		const SimpleParticle &	part2 )

Return the square of the distance between particles at equal time.

Makes Lorentz boost into the pair rest frame, then propagates the earlier particle to other particle's time, and computed the square of the distance between particles at that time.

Parameters

part1	First particle
part2	Second particle

Definition at line 242 of file ParticleDecaysMC.cpp.

◆ ShuffleDecayProducts()

void thermalfist::ParticleDecaysMC::ShuffleDecayProducts	(	std::vector< double > &	masses,
		std::vector< long long > &	pdgs )

Shuffles the decay products.

Currently used for four+ body decays to avoid having asymmetry in momentum distributions of decay products due to non-exact current implementation of these decays.

Parameters

masses	Masses of the decay products (in GeV)
pdgs	Pdg codes of the decay products

Definition at line 228 of file ParticleDecaysMC.cpp.

◆ TernaryThreeBodym12Maximum()

double thermalfist::ParticleDecaysMC::TernaryThreeBodym12Maximum	(	double	M,
		double	m1,
		double	m2,
		double	m3 )

Determines the maximum of the \(m_{12}\) probability density function used in a three-body decay.

Uses ternary search.

Parameters

M	Mass of the decaying particle
m1	Mass of the first daughter particle
m2	Mass of the first daughter particle
m3	Mass of the first daughter particle

Returns: Maximum of the \(m_{12}\) probability density function

Definition at line 24 of file ParticleDecaysMC.cpp.

◆ ThreeBodym12F2()

double thermalfist::ParticleDecaysMC::ThreeBodym12F2	(	double	m12,
		double	M,
		double	m1,
		double	m2,
		double	m3 )

Square of the \(m_{12}\) probability density function used in a three-body decay (unnormalized)

Parameters

m12	Invariant mass of the leading two daughter particles in a three-body decay
M	Mass of the decaying particle
m1	Mass of the first daughter particle
m2	Mass of the first daughter particle
m3	Mass of the first daughter particle

Returns: Square of the probability density for \(m_{12}\)

Definition at line 18 of file ParticleDecaysMC.cpp.

◆ TwoBodyDecay()

std::vector< SimpleParticle > thermalfist::ParticleDecaysMC::TwoBodyDecay	(	const SimpleParticle &	Mother,
		double	m1,
		long long	pdg1,
		double	m2,
		long long	pdg2 )

Samples the decay products of a two-body decay.

Parameters

Mother	The decaying particle
m1	Mass of the first daughter (in GeV)
pdg1	Pdg code of the first daughter
m2	Mass of the second daughter (in GeV)
pdg2	Pdg code of the second daughter

Returns: std::vector<SimpleParticle> Two-component vector of decay products

Definition at line 110 of file ParticleDecaysMC.cpp.

Variable Documentation

◆ threebodysucc

int thermalfist::ParticleDecaysMC::threebodysucc = 0

Used for debugging the succes rate in the rejection sampling of \(m_{12}\).

Definition at line 44 of file ParticleDecaysMC.cpp.

◆ threebodytot

int thermalfist::ParticleDecaysMC::threebodytot = 0

Definition at line 49 of file ParticleDecaysMC.h.

Functions

Variables

Detailed Description

Function Documentation

◆ ComputeDCA()

◆ GetRandomThreeBodym12()

◆ LorentzBoost()

◆ LorentzBoostMomentaAndCoordinates()

◆ LorentzBoostMomentumOnly()

◆ ManyBodyDecay()

◆ ParticleDistanceSquared()

◆ ShuffleDecayProducts()

◆ TernaryThreeBodym12Maximum()

◆ ThreeBodym12F2()

◆ TwoBodyDecay()

Variable Documentation

◆ threebodysucc

◆ threebodytot