The MEPP2GammaGamma class implements the production of photon pairs in hadron hadron collisions. More...

#include <MEPP2GammaGamma.h>

Inheritance diagram for Herwig::MEPP2GammaGamma:

[legend]

Public Member Functions
	MEPP2GammaGamma ()
	The default constructor.

Virtual functions required by the MEBase class.
virtual unsigned int	orderInAlphaS () const
	Return the order in \(\alpha_S\) in which this matrix element is given.

virtual unsigned int	orderInAlphaEW () const
	Return the order in \(\alpha_{EW}\) in which this matrix element is given.

virtual double	me2 () const
	The matrix element for the kinematical configuration previously provided by the last call to setKinematics(), suitably scaled by sHat() to give a dimension-less number.

virtual Energy2	scale () const
	Return the scale associated with the last set phase space point.

virtual void	getDiagrams () const
	Add all possible diagrams with the add() function.

virtual Selector< DiagramIndex >	diagrams (const DiagramVector &dv) const
	Get diagram selector.

virtual Selector< const ColourLines * >	colourGeometries (tcDiagPtr diag) const
	Return a Selector with possible colour geometries for the selected diagram weighted by their relative probabilities.

virtual void	constructVertex (tSubProPtr)
	Construct the vertex of spin correlations.

Public Member Functions inherited from Herwig::HwMEBase
	HwMEBase ()
	Default constructor.

virtual int	nDim () const
	The number of internal degreed of freedom used in the matrix element.

virtual bool	generateKinematics (const double *r)
	Generate internal degrees of freedom given 'nDim()' uniform random numbers in the interval ]0,1[.

virtual CrossSection	dSigHatDR () const
	Return the matrix element for the kinematical configuation previously provided by the last call to setKinematics().

virtual void	setKinematics ()
	Set the typed and momenta of the incoming and outgoing partons to be used in subsequent calls to me() and colourGeometries() according to the associated XComb object.

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, ShowerInteraction)
	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.

Public Member Functions inherited from ThePEG::MEBase
virtual unsigned int	orderInAlphaS () const=0

virtual unsigned int	orderInAlphaEW () const=0

virtual double	me2 () const=0

virtual Energy2	scale () const=0

virtual double	alphaS () const

virtual double	alphaEM () const

void	setKinematics (tPPair in, const PVector &out)

virtual void	setKinematics ()

virtual void	constructVertex (tSubProPtr sub)

virtual void	constructVertex (tSubProPtr sub, const ColourLines *cl)

virtual int	nDim () const

virtual bool	generateKinematics (const double *r)=0

virtual bool	wantCMS () const

virtual bool	headCuts () const

virtual bool	ignoreCuts () const

virtual bool	apply () const

virtual CrossSection	dSigHatDR () const=0

virtual map< string, double >	generateOptionalWeights ()

virtual bool	haveX1X2 () const

virtual bool	havePDFWeight1 () const

virtual bool	havePDFWeight2 () const

virtual bool	keepRandomNumbers () const

virtual void	generateSubCollision (SubProcess &)

virtual void	clearKinematics ()

virtual void	getDiagrams () const=0

virtual bool	noMirror () const

const DiagramVector &	diagrams () const

virtual Selector< const ColourLines * >	colourGeometries (tcDiagPtr diag) const=0

virtual const ColourLines &	selectColourGeometry (tcDiagPtr diag) const

virtual Selector< DiagramIndex >	diagrams (const DiagramVector &) const

virtual DiagramIndex	diagram (const DiagramVector &) const

bool	reweighted () const

double	reWeight () const

double	preWeight () const

void	addReweighter (tReweightPtr rw)

void	addPreweighter (tReweightPtr rw)

Ptr< Amplitude >::pointer	amplitude () const

void	amplitude (Ptr< Amplitude >::pointer amp)

Energy2	sHat () const

double	preweight () const

virtual void	flushCaches ()

virtual StdXCombPtr	makeXComb (Energy newMaxEnergy, const cPDPair &inc, tEHPtr newEventHandler, tSubHdlPtr newSubProcessHandler, tPExtrPtr newExtractor, tCascHdlPtr newCKKW, const PBPair &newPartonBins, tCutsPtr newCuts, const DiagramVector &newDiagrams, bool mir, const PartonPairVec &allPBins, tStdXCombPtr newHead=tStdXCombPtr(), tMEPtr newME=tMEPtr())

virtual StdXCombPtr	makeXComb (tStdXCombPtr newHead, const PBPair &newPartonBins, const DiagramVector &newDiagrams, tMEPtr newME=tMEPtr())

virtual void	fillProjectors ()

virtual void	setXComb (tStdXCombPtr)

const DVector &	meInfo () const

void	meInfo (const DVector &info) const

virtual int	maxMultCKKW () const

virtual int	minMultCKKW () const

virtual void	maxMultCKKW (int mult)

virtual void	minMultCKKW (int mult)

virtual void	setVetoScales (tSubProPtr) const

virtual unsigned int	orderInAlphaS () const=0

virtual unsigned int	orderInAlphaEW () const=0

virtual double	me2 () const=0

virtual Energy2	scale () const=0

virtual double	alphaS () const

virtual double	alphaEM () const

void	setKinematics (tPPair in, const PVector &out)

virtual void	setKinematics ()

virtual void	constructVertex (tSubProPtr sub)

virtual void	constructVertex (tSubProPtr sub, const ColourLines *cl)

virtual int	nDim () const

virtual bool	generateKinematics (const double *r)=0

virtual bool	wantCMS () const

virtual bool	headCuts () const

virtual bool	ignoreCuts () const

virtual bool	apply () const

virtual CrossSection	dSigHatDR () const=0

virtual map< string, double >	generateOptionalWeights ()

virtual bool	haveX1X2 () const

virtual bool	havePDFWeight1 () const

virtual bool	havePDFWeight2 () const

virtual bool	keepRandomNumbers () const

virtual void	generateSubCollision (SubProcess &)

virtual void	clearKinematics ()

virtual void	getDiagrams () const=0

virtual bool	noMirror () const

const DiagramVector &	diagrams () const

virtual Selector< const ColourLines * >	colourGeometries (tcDiagPtr diag) const=0

virtual const ColourLines &	selectColourGeometry (tcDiagPtr diag) const

virtual Selector< DiagramIndex >	diagrams (const DiagramVector &) const

virtual DiagramIndex	diagram (const DiagramVector &) const

bool	reweighted () const

double	reWeight () const

double	preWeight () const

void	addReweighter (tReweightPtr rw)

void	addPreweighter (tReweightPtr rw)

Ptr< Amplitude >::pointer	amplitude () const

void	amplitude (Ptr< Amplitude >::pointer amp)

Energy2	sHat () const

double	preweight () const

virtual void	flushCaches ()

virtual StdXCombPtr	makeXComb (Energy newMaxEnergy, const cPDPair &inc, tEHPtr newEventHandler, tSubHdlPtr newSubProcessHandler, tPExtrPtr newExtractor, tCascHdlPtr newCKKW, const PBPair &newPartonBins, tCutsPtr newCuts, const DiagramVector &newDiagrams, bool mir, const PartonPairVec &allPBins, tStdXCombPtr newHead=tStdXCombPtr(), tMEPtr newME=tMEPtr())

virtual StdXCombPtr	makeXComb (tStdXCombPtr newHead, const PBPair &newPartonBins, const DiagramVector &newDiagrams, tMEPtr newME=tMEPtr())

virtual void	fillProjectors ()

virtual void	setXComb (tStdXCombPtr)

const DVector &	meInfo () const

void	meInfo (const DVector &info) const

virtual int	maxMultCKKW () const

virtual int	minMultCKKW () const

virtual void	maxMultCKKW (int mult)

virtual void	minMultCKKW (int mult)

virtual void	setVetoScales (tSubProPtr) const

void	persistentOutput (PersistentOStream &os) const

void	persistentInput (PersistentIStream &is, int version)

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

Public Member Functions inherited from ThePEG::LastXCombInfo< StandardXComb >
const XC &	lastXComb () const

const XC &	lastXComb () const

tXCPtr	lastXCombPtr () const

tXCPtr	lastXCombPtr () const

const XC &	lastHeadXComb () const

const XC &	lastHeadXComb () const

tXCPtr	lastHeadXCombPtr () const

tXCPtr	lastHeadXCombPtr () const

const EventHandler &	lastEventHandler () const

const EventHandler &	lastEventHandler () const

tPExtrPtr	lastExtractor () const

tPExtrPtr	lastExtractor () const

PDFT	pdf (tcPPtr parton) const

PDFT	pdf (tcPPtr parton) const

const Cuts &	lastCuts () const

const Cuts &	lastCuts () const

tCutsPtr	lastCutsPtr () const

tCutsPtr	lastCutsPtr () const

const PPair &	lastParticles () const

const PPair &	lastParticles () const

Energy2	lastS () const

Energy2	lastS () const

const PPair &	lastPartons () const

const PPair &	lastPartons () const

Energy2	lastSHat () const

Energy2	lastSHat () const

double	lastTau () const

double	lastTau () const

double	lastY () const

double	lastY () const

double	lastP1 () const

double	lastP1 () const

double	lastP2 () const

double	lastP2 () const

double	lastL1 () const

double	lastL1 () const

double	lastL2 () const

double	lastL2 () const

double	lastX1 () const

double	lastX1 () const

double	lastX2 () const

double	lastX2 () const

double	lastE1 () const

double	lastE1 () const

double	lastE2 () const

double	lastE2 () const

double	lastFL1L2 () const

double	lastFL1L2 () const

Energy2	lastScale () const

double	lastAlphaS () const

double	lastAlphaEM () const

const vector< Lorentz5Momentum > &	meMomenta () const

double	lastME2 () const

double	lastPreweight () const

double	jacobian () const

CrossSection	lastMECrossSection () const

double	lastMEPDFWeight () const

double	lastMECouplings () const

tSubProPtr	subProcess () const

const cPDVector &	mePartonData () 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::HwMEBase
Energy2	tHat () const
	Return the \(\hat{t}\) of the last set phase space point.

Energy2	uHat () const
	Return the \(\hat{u}\) of the last set phase space point.

double	phi () const
	Return the azimuth angle of the last set phase space point.

void	tHat (Energy2 e2)
	Set the \(\hat{t}\) of the last set phase space point.

void	uHat (Energy2 e2)
	Set the \(\hat{u}\) of the last set phase space point.

void	phi (double phi)
	Set the azimuth angle of the last set phase space point.

void	massOption (vector< unsigned int > iopt)
	Set the treatment of the outgoing masses.

void	rescalingOption (unsigned int iopt)
	Rescaled momenta for the helicity ME.

bool	rescaleMomenta (const vector< Lorentz5Momentum > &, const cPDVector &)
	rescale the momenta for the computation of the helicity matrix element

const vector< Lorentz5Momentum > &	rescaledMomenta () const
	Access to the rescaled momenta.

bool	generateMasses (vector< Energy > &masses, double &mjac, const double *r)
	Generate the masses of the particles.

virtual double	getCosTheta (double cthmin, double cthmax, const double r)
	Used internally by generateKinematics, after calculating the limits on cos(theta).

Protected Member Functions inherited from ThePEG::MEBase
virtual void	doinit ()

virtual void	doinitrun ()

void	add (DiagPtr dp) const

vector< Lorentz5Momentum > &	meMomenta ()

void	lastME2 (double v) const

void	lastPreweight (double w) const

void	lastMECrossSection (CrossSection v) const

void	lastMEPDFWeight (double v) const

void	lastMECouplings (double v) const

void	jacobian (double j)

void	use (tcMEPtr other)

void	useDiagrams (tcMEPtr other) const

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.
AbstractFFVVertexPtr	_photonvertex
	Pointer to the quark-antiquark-photon vertex.

unsigned int	_maxflavour
	Maximum PDG code of the quarks allowed.

unsigned int	_process
	Option for which processes to include.

ProductionMatrixElement	_me
	Matrix element for spin correlations.

double	_diagwgt [2]
	weights for the different quark annhilation diagrams

double	scalePreFactor_
	Scale prefactor.

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

double	qqbarME (vector< SpinorWaveFunction > &fin, vector< SpinorBarWaveFunction > &ain, vector< VectorWaveFunction > &p1, vector< VectorWaveFunction > &p2, bool me) const
	Members to return the matrix elements for the different subprocesses.

double	ggME (vector< VectorWaveFunction > &g1, vector< VectorWaveFunction > &g2, vector< VectorWaveFunction > &p1, vector< VectorWaveFunction > &p2, bool me) const
	Matrix element for \(gg \to \gamma\gamma\).

Complex	ggme (Energy2 s, Energy2 t, Energy2 u) const
	\(gg\to\gamma\gamma\) matrix element for the \(++++\) helicity configuration.

MEPP2GammaGamma &	operator= (const MEPP2GammaGamma &)=delete
	The assignment operator is private and must never be called.

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 ()
	The standard Init function used to initialize the interfaces.

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

Public Types inherited from ThePEG::MEBase
typedef vector< DiagPtr >	DiagramVector

typedef DiagramVector::size_type	DiagramIndex

typedef vector< ReweightPtr >	ReweightVector

Public Types inherited from ThePEG::InterfacedBase
enum	InitState

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

Public Types inherited from ThePEG::LastXCombInfo< StandardXComb >
typedef ThePEG::Ptr< XC >::pointer	XCPtr

typedef ThePEG::Ptr< XC >::const_pointer	cXCPtr

typedef ThePEG::Ptr< XC >::transient_pointer	tXCPtr

typedef ThePEG::Ptr< XC >::transient_const_pointer	tcXCPtr

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

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

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)

Protected Attributes inherited from ThePEG::LastXCombInfo< StandardXComb >
XCPtr	theLastXComb

Detailed Description

The MEPP2GammaGamma class implements the production of photon pairs in hadron hadron collisions.

See also: The interfaces defined for MEPP2GammaGamma.

Definition at line 34 of file MEPP2GammaGamma.h.

Constructor & Destructor Documentation

◆ MEPP2GammaGamma()

Herwig::MEPP2GammaGamma::MEPP2GammaGamma ( )

inline

The default constructor.

Definition at line 41 of file MEPP2GammaGamma.h.

References Herwig::HwMEBase::massOption().

Member Function Documentation

◆ clone()

virtual IBPtr Herwig::MEPP2GammaGamma::clone ( ) const

protectedvirtual

Make a simple clone of this object.

Returns: a pointer to the new object.

Implements ThePEG::InterfacedBase.

◆ colourGeometries()

virtual Selector< const ColourLines * > Herwig::MEPP2GammaGamma::colourGeometries ( tcDiagPtr diag ) const

virtual

Return a Selector with possible colour geometries for the selected diagram weighted by their relative probabilities.

Parameters

diag	the diagram chosen.

Returns: the possible colour geometries weighted by their relative probabilities.

Implements ThePEG::MEBase.

◆ constructVertex()

virtual void Herwig::MEPP2GammaGamma::constructVertex ( tSubProPtr )

virtual

Construct the vertex of spin correlations.

Reimplemented from ThePEG::MEBase.

◆ diagrams()

virtual Selector< DiagramIndex > Herwig::MEPP2GammaGamma::diagrams ( const DiagramVector & dv ) const

virtual

Get diagram selector.

With the information previously supplied with the setKinematics method, a derived class may optionally override this method to weight the given diagrams with their (although certainly not physical) relative probabilities.

Parameters

dv	the diagrams to be weighted.

Returns: a Selector relating the given diagrams to their weights.

Reimplemented from ThePEG::MEBase.

◆ doinit()

virtual void Herwig::MEPP2GammaGamma::doinit ( )

protectedvirtual

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

Exceptions

InitException if object could not be initialized properly.

Reimplemented from ThePEG::MEBase.

◆ fullclone()

virtual IBPtr Herwig::MEPP2GammaGamma::fullclone ( ) const

protectedvirtual

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.

◆ getDiagrams()

virtual void Herwig::MEPP2GammaGamma::getDiagrams ( ) const

virtual

Add all possible diagrams with the add() function.

Implements ThePEG::MEBase.

◆ ggme()

Complex Herwig::MEPP2GammaGamma::ggme	(	Energy2	s,
		Energy2	t,
		Energy2	u
	)		const

inlineprivate

\(gg\to\gamma\gamma\) matrix element for the \(++++\) helicity configuration.

Parameters

s	The \(s\) invariant
t	The \(t\) invariant
u	The \(u\) invariant

Definition at line 197 of file MEPP2GammaGamma.h.

References ThePEG::Constants::pi, ThePEG::sqr(), and ThePEG::ZERO.

◆ ggME()

double Herwig::MEPP2GammaGamma::ggME	(	vector< VectorWaveFunction > &	g1,
		vector< VectorWaveFunction > &	g2,
		vector< VectorWaveFunction > &	p1,
		vector< VectorWaveFunction > &	p2,
		bool	me
	)		const

private

Matrix element for \(gg \to \gamma\gamma\).

Parameters

g1	Polarization vectors for the first incoming gluon
g2	Polarization vectors for the second incoming gluon
p1	Polarization vectors for the first outgoing photon
p2	Polarization vectors for the second outgoing photon
me	Whether or not to calculate the matrix element for spin correlations

◆ Init()

static void Herwig::MEPP2GammaGamma::Init ( )

static

The standard Init function used to initialize the interfaces.

Called exactly once for each class by the class description system before the main function starts or when this class is dynamically loaded.

◆ me2()

virtual double Herwig::MEPP2GammaGamma::me2 ( ) const

virtual

The matrix element for the kinematical configuration previously provided by the last call to setKinematics(), suitably scaled by sHat() to give a dimension-less number.

Returns: the matrix element scaled with sHat() to give a dimensionless number.

Implements ThePEG::MEBase.

◆ operator=()

MEPP2GammaGamma & Herwig::MEPP2GammaGamma::operator= ( const MEPP2GammaGamma & )

privatedelete

The assignment operator is private and must never be called.

In fact, it should not even be implemented.

◆ orderInAlphaEW()

virtual unsigned int Herwig::MEPP2GammaGamma::orderInAlphaEW ( ) const

virtual

Return the order in \(\alpha_{EW}\) in which this matrix element is given.

Implements ThePEG::MEBase.

◆ orderInAlphaS()

virtual unsigned int Herwig::MEPP2GammaGamma::orderInAlphaS ( ) const

virtual

Return the order in \(\alpha_S\) in which this matrix element is given.

Implements ThePEG::MEBase.

◆ persistentInput()

void Herwig::MEPP2GammaGamma::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::MEPP2GammaGamma::persistentOutput ( PersistentOStream & os ) const

Function used to write out object persistently.

Parameters

os	the persistent output stream written to.

◆ qqbarME()

double Herwig::MEPP2GammaGamma::qqbarME	(	vector< SpinorWaveFunction > &	fin,
		vector< SpinorBarWaveFunction > &	ain,
		vector< VectorWaveFunction > &	p1,
		vector< VectorWaveFunction > &	p2,
		bool	me
	)		const

private

Members to return the matrix elements for the different subprocesses.

Matrix element for \(q\bar{q}\to \gamma\gamma\).

Parameters

fin	Spinors for incoming quark
ain	Spinors for incoming antiquark
p1	Polarization vectors for the first outgoing photon
p2	Polarization vectors for the second outgoing photon
me	Whether or not to calculate the matrix element for spin correlations

◆ scale()

virtual Energy2 Herwig::MEPP2GammaGamma::scale ( ) const

virtual

Return the scale associated with the last set phase space point.

Implements ThePEG::MEBase.

Member Data Documentation

◆ _diagwgt

double Herwig::MEPP2GammaGamma::_diagwgt[2]

mutableprivate

weights for the different quark annhilation diagrams

Definition at line 241 of file MEPP2GammaGamma.h.

◆ _maxflavour

unsigned int Herwig::MEPP2GammaGamma::_maxflavour

private

Maximum PDG code of the quarks allowed.

Definition at line 226 of file MEPP2GammaGamma.h.

◆ _me

ProductionMatrixElement Herwig::MEPP2GammaGamma::_me

private

Matrix element for spin correlations.

Definition at line 236 of file MEPP2GammaGamma.h.

◆ _photonvertex

AbstractFFVVertexPtr Herwig::MEPP2GammaGamma::_photonvertex

private

Pointer to the quark-antiquark-photon vertex.

Definition at line 221 of file MEPP2GammaGamma.h.

◆ _process

unsigned int Herwig::MEPP2GammaGamma::_process

private

Option for which processes to include.

Definition at line 231 of file MEPP2GammaGamma.h.

◆ scalePreFactor_

double Herwig::MEPP2GammaGamma::scalePreFactor_

private

Scale prefactor.

Definition at line 246 of file MEPP2GammaGamma.h.

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

MEPP2GammaGamma.h

Public Member Functions

Protected Member Functions

Standard Interfaced functions.

Functions used by the persistent I/O system.

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ MEPP2GammaGamma()

Member Function Documentation

◆ clone()

◆ colourGeometries()

◆ constructVertex()

◆ diagrams()

◆ doinit()

◆ fullclone()

◆ getDiagrams()

◆ ggme()

◆ ggME()

◆ Init()

◆ me2()

◆ operator=()

◆ orderInAlphaEW()

◆ orderInAlphaS()

◆ persistentInput()

◆ persistentOutput()

◆ qqbarME()

◆ scale()

Member Data Documentation

◆ _diagwgt

◆ _maxflavour

◆ _me

◆ _photonvertex

◆ _process

◆ scalePreFactor_