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Herwig++  2.7.0
Herwig::MEPP2GammaGamma Class Reference

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

#include <MEPP2GammaGamma.h>

Inheritance diagram for Herwig::MEPP2GammaGamma:

List of all members.

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< DiagramIndexdiagrams (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.
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 Public Member Functions

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

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

Private Member Functions

Complex ggme (Energy2 s, Energy2 t, Energy2 u) const
 $gg\to\gamma\gamma$ matrix element for the $++++$ helicity configuration.
MEPP2GammaGammaoperator= (const MEPP2GammaGamma &)
 The assignment operator is private and must never be called.
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 $gg \to \gamma\gamma$.

Private Attributes

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

Static Private Attributes

static ClassDescription
< MEPP2GammaGamma
initMEPP2GammaGamma
 The static object used to initialize the description of this class.

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.


Member Function Documentation

virtual IBPtr Herwig::MEPP2GammaGamma::clone ( ) const [protected, virtual]

Make a simple clone of this object.

Returns:
a pointer to the new object.

Implements ThePEG::InterfacedBase.

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

Implements ThePEG::MEBase.

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

Reimplemented from ThePEG::MEBase.

virtual void Herwig::MEPP2GammaGamma::doinit ( ) [protected, virtual]

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

Exceptions:
InitExceptionif object could not be initialized properly.

Reimplemented from ThePEG::InterfacedBase.

virtual IBPtr Herwig::MEPP2GammaGamma::fullclone ( ) const [protected, virtual]

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.

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:
g1Polarization vectors for the first incoming gluon
g2Polarization vectors for the second incoming gluon
p1Polarization vectors for the first outgoing photon
p2Polarization vectors for the second outgoing photon
meWhether or not to calculate the matrix element for spin correlations
Complex Herwig::MEPP2GammaGamma::ggme ( Energy2  s,
Energy2  t,
Energy2  u 
) const [inline, private]

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

Parameters:
sThe $s$ invariant
tThe $t$ invariant
uThe $u$ invariant

Definition at line 197 of file MEPP2GammaGamma.h.

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

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.

Reimplemented from Herwig::HwMEBase.

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.

MEPP2GammaGamma& Herwig::MEPP2GammaGamma::operator= ( const MEPP2GammaGamma ) [private]

The assignment operator is private and must never be called.

In fact, it should not even be implemented.

Function used to read in object persistently.

Parameters:
isthe persistent input stream read from.
versionthe version number of the object when written.

Reimplemented from Herwig::HwMEBase.

Function used to write out object persistently.

Parameters:
osthe persistent output stream written to.

Reimplemented from Herwig::HwMEBase.

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:
finSpinors for incoming quark
ainSpinors for incoming antiquark
p1Polarization vectors for the first outgoing photon
p2Polarization vectors for the second outgoing photon
meWhether or not to calculate the matrix element for spin correlations

Member Data Documentation

The static object used to initialize the description of this class.

Indicates that this is a concrete class with persistent data.

Definition at line 214 of file MEPP2GammaGamma.h.


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