The VectorMeson2FermionDecayer class is designed for the decay of a vector meson to a fermion-antifermion pair. More...

#include <VectorMeson2FermionDecayer.h>

Inheritance diagram for Herwig::VectorMeson2FermionDecayer:

[legend]

Public Member Functions
	VectorMeson2FermionDecayer ()
	Default constructor.

virtual int	modeNumber (bool &cc, tcPDPtr parent, const tPDVector &children) const
	Which of the possible decays is required.

double	me2 (const int ichan, const Particle &part, const tPDVector &outgoing, const vector< Lorentz5Momentum > &momenta, MEOption meopt) const
	Return the matrix element squared for a given mode and phase-space channel.

virtual void	constructSpinInfo (const Particle &part, ParticleVector outgoing) const
	Construct the SpinInfos for the particles produced in the decay.

bool	twoBodyMEcode (const DecayMode &dm, int &mecode, double &coupling) const
	Specify the \(1\to2\) matrix element to be used in the running width calculation.

virtual void	dataBaseOutput (ofstream &os, bool header) const
	Output the setup information for the particle database.

Public Member Functions inherited from Herwig::DecayIntegrator
	DecayIntegrator ()
	The default constructor.

virtual bool	accept (tcPDPtr parent, const tPDVector &children) const
	Check if this decayer can perfom the decay for a particular mode.

virtual ParticleVector	decay (const Particle &parent, const tPDVector &children) const
	For a given decay mode and a given particle instance, perform the decay and return the decay products.

virtual int	modeNumber (bool &cc, tcPDPtr parent, const tPDVector &children) const =0
	Which of the possible decays is required.

int	imode () const
	The mode being used for this decay.

void	addMode (PhaseSpaceModePtr mode) const
	Add a phase-space mode to the list.

virtual double	me2 (const int ichan, const Particle &part, const tPDVector &outgoing, const vector< Lorentz5Momentum > &momenta, MEOption meopt) const =0
	Return the matrix element squared for a given mode and phase-space channel.

virtual void	constructSpinInfo (const Particle &part, ParticleVector outgoing) const =0
	Construct the SpinInfos for the particles produced in the decay.

virtual void	dataBaseOutput (ofstream &os, bool header) const
	Output the setup information for the particle database.

void	setPartialWidth (const DecayMode &dm, int imode)
	Set the code for the partial width.

virtual bool	twoBodyMEcode (const DecayMode &, int &mecode, double &coupling) const
	Specify the \(1\to2\) matrix element to be used in the running width calculation.

virtual WidthCalculatorBasePtr	threeBodyMEIntegrator (const DecayMode &dm) const
	Method to return an object to calculate the 3 (or higher body) partial width.

virtual double	threeBodyMatrixElement (const int imode, const Energy2 q2, const Energy2 s3, const Energy2 s2, const Energy2 s1, const Energy m1, const Energy m2, const Energy m3) const
	The matrix element to be integrated for the three-body decays as a function of the invariant masses of pairs of the outgoing particles.

virtual InvEnergy	threeBodydGammads (const int imode, const Energy2 q2, const Energy2 s, const Energy m1, const Energy m2, const Energy m3) const
	The differential three body decay rate with one integral performed.

int	findMode (const DecayMode &dm)
	Finds the phase-space mode corresponding to a given decay mode.

ParticleVector	generatePhotons (const Particle &p, ParticleVector children)
	Members for the generation of QED radiation in the decays.

bool	canGeneratePhotons ()
	check if photons can be generated in the decay

virtual double	oneLoopVirtualME (unsigned int imode, const Particle &part, const ParticleVector &products)
	The one-loop virtual correction.

bool	hasOneLoopME ()
	Whether or not the one loop matrix element is implemented.

virtual InvEnergy2	realEmissionME (unsigned int imode, const Particle &part, ParticleVector &products, unsigned int iemitter, double ctheta, double stheta, const LorentzRotation &rot1, const LorentzRotation &rot2)
	The real emission matrix element.

bool	hasRealEmissionME ()
	Whether or not the real emission matrix element is implemented.

bool	warnings () const

void	persistentOutput (PersistentOStream &os) const
	Function used to write out object persistently.

void	persistentInput (PersistentIStream &is, int version)
	Function used to read in object persistently.

Public Member Functions inherited from Herwig::HwDecayerBase
	HwDecayerBase ()
	The default constructor.

virtual bool	accept (const DecayMode &dm) const
	Check if this decayer can perfom the decay specified by the given decay mode.

virtual ParticleVector	decay (const DecayMode &dm, const Particle &p) const
	Perform a decay for a given DecayMode and a given Particle instance.

virtual POWHEGType	hasPOWHEGCorrection ()
	Has a POWHEG style correction.

virtual bool	hasMECorrection ()
	Has an old fashioned ME correction.

virtual void	initializeMECorrection (RealEmissionProcessPtr, double &, double &)
	Initialize the ME correction.

virtual RealEmissionProcessPtr	applyHardMatrixElementCorrection (RealEmissionProcessPtr)
	Apply the hard matrix element correction to a given hard process or decay.

virtual bool	softMatrixElementVeto (PPtr parent, PPtr progenitor, const bool &fs, const Energy &highestpT, const vector< tcPDPtr > &ids, const double &z, const Energy &scale, const Energy &pT)
	Apply the soft matrix element correction.

virtual RealEmissionProcessPtr	generateHardest (RealEmissionProcessPtr)
	Apply the POWHEG style correction.

void	persistentOutput (PersistentOStream &os) const
	Function used to write out object persistently.

void	persistentInput (PersistentIStream &is, int version)
	Function used to read in object persistently.

bool	initialize () const
	Access to the initialize variable.

bool	databaseOutput () const
	Access the database output variable.

Public Member Functions inherited from ThePEG::Decayer
void	persistentOutput (PersistentOStream &os) const

void	persistentInput (PersistentIStream &is, int version)

virtual bool	accept (const DecayMode &dm) const=0

virtual bool	needsFullStep () const

virtual ParticleVector	decay (const DecayMode &dm, const Particle &p) const=0

virtual ParticleVector	decay (const DecayMode &dm, const Particle &p, Step &step) const

virtual double	brat (const DecayMode &dm, const ParticleData &pd, double oldbrat) const

virtual double	brat (const DecayMode &dm, const Particle &p, double oldbrat) const

virtual ParticleVector	getChildren (const DecayMode &dm, const Particle &parent) const

virtual void	finalBoost (const Particle &parent, const ParticleVector &children) const

virtual void	setScales (const Particle &parent, const ParticleVector &children) const

Ptr< Amplitude >::pointer	amplitude () const

Public Member Functions inherited from ThePEG::HandlerBaseT< UseRandom >
double	rnd () const

double	rnd (double xu) const

double	rnd (double xl, double xu) const

bool	rndbool () const

bool	rndbool (double p) const

bool	rndbool (double p1, double p2) const

int	rndsign (double p1, double p2, double p3) const

int	rnd2 (double p0, double p1) const

int	rnd3 (double p0, double p1, double p2) const

int	rnd4 (double p0, double p1, double p2, double p3) const

long	irnd (long xu=2) const

long	irnd (long xl, long xu) const

const StandardModelBase &	SM () const

tSMPtr	standardModel () const

Public Member Functions inherited from ThePEG::Interfaced
virtual bool	defaultInit ()

PPtr	getParticle (PID) const

PDPtr	getParticleData (PID) const

bool	used () const

void	useMe () const

tEGPtr	generator () const

void	persistentOutput (PersistentOStream &os) const

void	persistentInput (PersistentIStream &is, int version)

PPtr	getParticle (PID) const

PDPtr	getParticleData (PID) const

bool	used () const

void	useMe () const

tEGPtr	generator () const

Public Member Functions inherited from ThePEG::InterfacedBase
string	fullName () const

string	name () const

string	path () const

string	comment () const

void	setup (istream &is)

void	update ()

void	init ()

virtual bool	preInitialize () const

void	initrun ()

void	finish ()

void	touch ()

void	reset ()

void	clear ()

InitState	state () const

bool	locked () const

bool	touched () const

virtual IBPtr	fullclone () const

void	persistentOutput (PersistentOStream &os) const

void	persistentInput (PersistentIStream &is, int version)

virtual void	debugme () const

void	update ()

void	init ()

virtual bool	preInitialize () const

void	initrun ()

void	finish ()

void	touch ()

void	reset ()

void	clear ()

InitState	state () const

bool	locked () const

bool	touched () const

virtual IBPtr	fullclone () const

Public Member Functions inherited from ThePEG::Base
void	debug () const

virtual void	debugme () const

Public Member Functions inherited from ThePEG::Pointer::ReferenceCounted
CounterType	referenceCount () const

Public Member Functions inherited from ThePEG::Named
	Named (const string &newName=string())

	Named (const Named &)=default

const string &	name () const

bool	operator== (const Named &other) const

bool	operator< (const Named &other) const

Protected Member Functions
Clone Methods.
virtual IBPtr	clone () const
	Make a simple clone of this object.

virtual IBPtr	fullclone () const
	Make a clone of this object, possibly modifying the cloned object to make it sane.

Protected Member Functions inherited from Herwig::DecayIntegrator
ParticleVector	generate (bool inter, bool cc, const unsigned int &imode, const Particle &inpart) const
	Generate the momenta for the decay.

void	imode (int in)
	Set the mode being use for this decay.

void	ME (DecayMEPtr in) const
	Set the helicity matrix element for the decay.

DecayMEPtr	ME () const
	The helicity amplitude matrix element for spin correlations.

void	resetIntermediate (tcPDPtr part, Energy mass, Energy width)
	Reset the properities of all intermediates.

Energy	initializePhaseSpaceMode (unsigned int imode, bool init, bool onShell=false) const
	Initialize the phase-space mode.

void	generateIntermediates (bool in)
	Methods to set variables in inheriting classes.

bool	generateIntermediates () const
	Set whether or not the intermediates are included.

void	hasOneLoopME (bool in)
	Whether or not the one loop matrix element is implemented.

void	hasRealEmissionME (bool in)
	Whether or not the real emission matrix element is implemented.

void	epsilonPS (Energy in)
	Set the epsilon parameter.

void	clearModes ()
	Clear the models.

unsigned int	numberModes () const
	Number of decay modes.

tPhaseSpaceModePtr	mode (unsigned int ix)
	Pointer to a mode.

tcPhaseSpaceModePtr	mode (unsigned int ix) const
	Pointer to a mode.

Protected Member Functions inherited from Herwig::HwDecayerBase
virtual void	dofinish ()
	Finalize this object.

void	fixRho (RhoDMatrix &) const
	Set rho to be diagonal if no correlations.

Protected Member Functions inherited from ThePEG::Interfaced
void	reporeg (IBPtr object, string name) const

bool	setDefaultReference (PtrT &ptr, string classname, string objectname)

	Interfaced (const string &newName)

	Interfaced (const Interfaced &i)

void	setGenerator (tEGPtr generator)

Protected Member Functions inherited from ThePEG::InterfacedBase
virtual void	readSetup (istream &is)

virtual void	doupdate ()

virtual void	doinit ()

virtual void	doinitrun ()

virtual void	dofinish ()

virtual IVector	getReferences ()

virtual void	rebind (const TranslationMap &)

virtual IBPtr	clone () const=0

	InterfacedBase (string newName)

	InterfacedBase (const InterfacedBase &i)

virtual void	readSetup (istream &is)

virtual void	doupdate ()

virtual void	doinit ()

virtual void	doinitrun ()

virtual void	dofinish ()

virtual IVector	getReferences ()

virtual void	rebind (const TranslationMap &)

Protected Member Functions inherited from ThePEG::Pointer::ReferenceCounted
	ReferenceCounted (const ReferenceCounted &)

ReferenceCounted &	operator= (const ReferenceCounted &)

Protected Member Functions inherited from ThePEG::Named
const Named &	operator= (const Named &other)

const string &	name (const string &newName)

Standard Interfaced functions.
vector< double >	coupling_
	coupling for a decay

vector< long >	incoming_
	the PDG codes for the incoming particles

vector< pair< long, long > >	outgoing_
	the PDG codes for the outgoing fermion-antifermion

vector< double >	maxweight_
	maximum weight for a decay

RhoDMatrix	rho_
	Spin density matrix.

vector< Helicity::LorentzPolarizationVector >	vectors_
	Polarization vectors for the decaying particle.

vector< Helicity::LorentzSpinor< SqrtEnergy > >	wave_
	Spinors for the decay products.

vector< Helicity::LorentzSpinorBar< SqrtEnergy > >	wavebar_
	barred spinors for the decay products

string	setUpDecayMode (string arg)
	Set the parameters for a decay mode.

virtual void	doinit ()
	Initialize this object after the setup phase before saving and EventGenerator to disk.

virtual void	doinitrun ()
	Initialize this object to the begining of the run phase.

VectorMeson2FermionDecayer &	operator= (const VectorMeson2FermionDecayer &)=delete
	Private and non-existent assignment operator.

Functions used by the persistent I/O system.
void	persistentOutput (PersistentOStream &os) const
	Function used to write out object persistently.

void	persistentInput (PersistentIStream &is, int version)
	Function used to read in object persistently.

static void	Init ()
	Standard Init function used to initialize the interfaces.

Additional Inherited Members
Public Types inherited from Herwig::DecayIntegrator
enum	MEOption { Initialize , Calculate , Terminate }
	Enum for the matrix element option. More...

Public Types inherited from Herwig::HwDecayerBase
enum	POWHEGType { No , ISR , FSR , Both }
	Virtual members to be overridden by inheriting classes which implement hard corrections. More...

Public Types inherited from ThePEG::InterfacedBase
enum	InitState

Public Types inherited from ThePEG::Pointer::ReferenceCounted
typedef unsigned int	CounterType

Static Public Member Functions inherited from Herwig::DecayIntegrator
static void	Init ()
	The standard Init function used to initialize the interfaces.

Static Public Member Functions inherited from Herwig::HwDecayerBase
static void	Init ()
	The standard Init function used to initialize the interfaces.

Static Public Member Functions inherited from ThePEG::Decayer
static void	Init ()

static ParticleVector	DecayParticle (tPPtr parent, Step &step, long maxtry=1000)

Static Public Member Functions inherited from ThePEG::HandlerBase
static void	Init ()

Static Public Member Functions inherited from ThePEG::Interfaced
static void	Init ()

Static Public Member Functions inherited from ThePEG::InterfacedBase
static void	Init ()

Static Public Member Functions inherited from ThePEG::Base
static void	Init ()

Public Attributes inherited from ThePEG::InterfacedBase
	initializing

	uninitialized

	initialized

	runready

Public Attributes inherited from ThePEG::Pointer::ReferenceCounted
const unsigned long	uniqueId

Static Protected Member Functions inherited from ThePEG::Interfaced
static void	registerRepository (IBPtr)

static void	registerRepository (IBPtr, string newName)

Detailed Description

The VectorMeson2FermionDecayer class is designed for the decay of a vector meson to a fermion-antifermion pair.

This class is mainly used for the decay of the vector mesons to electron and muon pairs but can also be used for the decay of charmonium, e.g. \(J/\psi\), or bottomonium decays to baryons, e.g. \(p\bar{p}\) and \(n\bar{n}\).

In this case the matrix element is taken to have the form

\[\mathcal{M} = g\epsilon_\mu \bar{u}(p_f)\gamma^\mu u(p_{\bar{f}}).\]

The incoming vector mesons together with their decay products and the coupling \(g\) can be specified using the interfaces for the class. The maximum weights for the decays can be calculated using the Initialize interface of the DecayIntegrator class or specified using the interface.

The incoming and outgoing particles, couplings and maximum weights for many of the common \(V\to f\bar{f}\) decays are specified in the default constructor.

See also: DecayIntegrator; The interfaces defined for VectorMeson2FermionDecayer.

Definition at line 46 of file VectorMeson2FermionDecayer.h.

Member Function Documentation

◆ clone()

virtual IBPtr Herwig::VectorMeson2FermionDecayer::clone ( ) const

inlineprotectedvirtual

Make a simple clone of this object.

Returns: a pointer to the new object.

Implements ThePEG::InterfacedBase.

Definition at line 132 of file VectorMeson2FermionDecayer.h.

◆ constructSpinInfo()

virtual void Herwig::VectorMeson2FermionDecayer::constructSpinInfo	(	const Particle &	part,
		ParticleVector	outgoing
	)		const

virtual

Construct the SpinInfos for the particles produced in the decay.

Implements Herwig::DecayIntegrator.

◆ dataBaseOutput()

virtual void Herwig::VectorMeson2FermionDecayer::dataBaseOutput	(	ofstream &	os,
		bool	header
	)		const

virtual

Output the setup information for the particle database.

Parameters

os	The stream to output the information to
header	Whether or not to output the information for MySQL

Reimplemented from Herwig::DecayIntegrator.

◆ doinit()

virtual void Herwig::VectorMeson2FermionDecayer::doinit ( )

protectedvirtual

Initialize this object after the setup phase before saving and EventGenerator to disk.

Exceptions

InitException if object could not be initialized properly.

Reimplemented from ThePEG::InterfacedBase.

◆ doinitrun()

virtual void Herwig::VectorMeson2FermionDecayer::doinitrun ( )

protectedvirtual

Initialize this object to the begining of the run phase.

Reimplemented from Herwig::DecayIntegrator.

◆ fullclone()

virtual IBPtr Herwig::VectorMeson2FermionDecayer::fullclone ( ) const

inlineprotectedvirtual

Make a clone of this object, possibly modifying the cloned object to make it sane.

Returns: a pointer to the new object.

Reimplemented from ThePEG::InterfacedBase.

Definition at line 138 of file VectorMeson2FermionDecayer.h.

◆ me2()

double Herwig::VectorMeson2FermionDecayer::me2	(	const int	ichan,
		const Particle &	part,
		const tPDVector &	outgoing,
		const vector< Lorentz5Momentum > &	momenta,
		MEOption	meopt
	)		const

virtual

Return the matrix element squared for a given mode and phase-space channel.

Parameters

ichan	The channel we are calculating the matrix element for.
part	The decaying Particle.
outgoing	The particles produced in the decay
momenta	The momenta of the particles produced in the decay
meopt	Option for the calculation of the matrix element

Returns: The matrix element squared for the phase-space configuration.

Implements Herwig::DecayIntegrator.

◆ modeNumber()

virtual int Herwig::VectorMeson2FermionDecayer::modeNumber	(	bool &	cc,
		tcPDPtr	parent,
		const tPDVector &	children
	)		const

virtual

Which of the possible decays is required.

Parameters

cc	Is this mode the charge conjugate
parent	The decaying particle
children	The decay products

Implements Herwig::DecayIntegrator.

◆ persistentInput()

void Herwig::VectorMeson2FermionDecayer::persistentInput	(	PersistentIStream &	is,
		int	version
	)

Function used to read in object persistently.

Parameters

is	the persistent input stream read from.
version	the version number of the object when written.

◆ persistentOutput()

void Herwig::VectorMeson2FermionDecayer::persistentOutput ( PersistentOStream & os ) const

Function used to write out object persistently.

Parameters

os	the persistent output stream written to.

◆ twoBodyMEcode()

bool Herwig::VectorMeson2FermionDecayer::twoBodyMEcode	(	const DecayMode &	dm,
		int &	mecode,
		double &	coupling
	)		const

virtual

Specify the \(1\to2\) matrix element to be used in the running width calculation.

Parameters

dm	The DecayMode
mecode	The code for the matrix element as described in the GenericWidthGenerator class, in this case 2.
coupling	The coupling for the matrix element.

Returns: True or False if this mode can be handled.

Reimplemented from Herwig::DecayIntegrator.

Member Data Documentation

◆ coupling_

vector<double> Herwig::VectorMeson2FermionDecayer::coupling_

private

coupling for a decay

Definition at line 177 of file VectorMeson2FermionDecayer.h.

◆ incoming_

vector<long> Herwig::VectorMeson2FermionDecayer::incoming_

private

the PDG codes for the incoming particles

Definition at line 182 of file VectorMeson2FermionDecayer.h.

◆ maxweight_

vector<double> Herwig::VectorMeson2FermionDecayer::maxweight_

private

maximum weight for a decay

Definition at line 192 of file VectorMeson2FermionDecayer.h.

◆ outgoing_

vector<pair<long,long> > Herwig::VectorMeson2FermionDecayer::outgoing_

private

the PDG codes for the outgoing fermion-antifermion

Definition at line 187 of file VectorMeson2FermionDecayer.h.

◆ rho_

RhoDMatrix Herwig::VectorMeson2FermionDecayer::rho_

mutableprivate

Spin density matrix.

Definition at line 197 of file VectorMeson2FermionDecayer.h.

◆ vectors_

vector<Helicity::LorentzPolarizationVector> Herwig::VectorMeson2FermionDecayer::vectors_

mutableprivate

Polarization vectors for the decaying particle.

Definition at line 202 of file VectorMeson2FermionDecayer.h.

◆ wave_

vector<Helicity::LorentzSpinor <SqrtEnergy> > Herwig::VectorMeson2FermionDecayer::wave_

mutableprivate

Spinors for the decay products.

Definition at line 207 of file VectorMeson2FermionDecayer.h.

◆ wavebar_

vector<Helicity::LorentzSpinorBar<SqrtEnergy> > Herwig::VectorMeson2FermionDecayer::wavebar_

mutableprivate

barred spinors for the decay products

Definition at line 212 of file VectorMeson2FermionDecayer.h.

The documentation for this class was generated from the following file:

VectorMeson2FermionDecayer.h

Public Member Functions

Protected Member Functions

Standard Interfaced functions.

Functions used by the persistent I/O system.

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ clone()

◆ constructSpinInfo()

◆ dataBaseOutput()

◆ doinit()

◆ doinitrun()

◆ fullclone()

◆ me2()

◆ modeNumber()

◆ persistentInput()

◆ persistentOutput()

◆ twoBodyMEcode()

Member Data Documentation

◆ coupling_

◆ incoming_

◆ maxweight_

◆ outgoing_

◆ rho_

◆ vectors_

◆ wave_

◆ wavebar_