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Herwig++  2.7.0
Herwig::MEee2gZ2qq Class Reference

The MEee2gZ2qq class implements the matrix element for $e^+e^-\to Z/\gamma \to q\bar{q}$ including spin correlations. More...

#include <MEee2gZ2qq.h>

Inheritance diagram for Herwig::MEee2gZ2qq:

List of all members.

Public Member Functions

 MEee2gZ2qq ()
 The default constructor.
virtual POWHEGType hasPOWHEGCorrection ()
 Members for hard corrections to the emission of QCD radiation.
virtual bool hasMECorrection ()
 Has an old fashioned ME correction.
virtual void initializeMECorrection (ShowerTreePtr, double &, double &)
 Initialize the ME correction.
virtual void applyHardMatrixElementCorrection (ShowerTreePtr)
 Apply the hard matrix element correction to a given hard process or decay.
virtual bool softMatrixElementVeto (ShowerProgenitorPtr initial, ShowerParticlePtr parent, Branching br)
 Apply the soft matrix element correction.
virtual HardTreePtr generateHardest (ShowerTreePtr)
 Apply the POWHEG style correction.
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

double loME (const vector< cPDPtr > &partons, const vector< Lorentz5Momentum > &momenta, bool first) const
 Calculate the matrix element for $e^-e^-\to q \bar q$.
ProductionMatrixElement HelicityME (vector< SpinorWaveFunction > &fin, vector< SpinorBarWaveFunction > &ain, vector< SpinorBarWaveFunction > &fout, vector< SpinorWaveFunction > &aout, double &me, double &cont, double &BW) const
 Member to calculate the matrix element.
double meRatio (vector< cPDPtr > partons, vector< Lorentz5Momentum > momenta, unsigned int iemitter, bool subtract=false) const
 The ratio of the matrix element for one additional jet over the leading order result.
InvEnergy2 realME (const vector< cPDPtr > &partons, const vector< Lorentz5Momentum > &momenta) const
 Calculate the matrix element for $e^-e^-\to q \bar q g$.
AbstractFFVVertexPtr FFZVertex () const
 Pointer to the fermion-antifermion Z vertex.
AbstractFFVVertexPtr FFPVertex () const
 Pointer to the fermion-antifermion photon vertex.
PDPtr Z0 () const
 Pointer to the particle data object for the Z.
PDPtr gamma () const
 Pointer to the particle data object for the photon.
PDPtr gluon () const
 Pointer to the particle data object for the gluon.
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.
virtual void rebind (const TranslationMap &trans)
 Rebind pointer to other Interfaced objects.
virtual IVector getReferences ()
 Return a vector of all pointers to Interfaced objects used in this object.

Private Member Functions

vector< Lorentz5Momentum > applyHard (const ParticleVector &p)
 Apply the hard matrix element.
double getHard (double &, double &)
 Get the weight for hard emission.
void setRho (double)
 Set the $\rho$ parameter.
void setKtildeSymm ()
 Set the $\tilde{\kappa}$ parameters symmetrically.
void setKtilde2 ()
 Set second $\tilde{\kappa}$, given the first.
void getXXbar (double kt, double z, double &x, double &xbar)
 Calculate $x_{q},x_{\bar{q}}$ from $\tilde{\kappa},z$.
double u (double)
 ????
MEee2gZ2qqoperator= (const MEee2gZ2qq &)
 The assignment operator is private and must never be called.
double getZfromX (double, double)
 Translate the variables from $x_q,x_{\bar{q}}$ to $\tilde{\kappa},z$.
double getKfromX (double, double)
 Calculate $\tilde{\kappa}$.
double qWeight (double x, double xbar)
 Soft weight.
double qbarWeight (double x, double xbar)
 Soft antiquark weight calculated from $x_{q},x_{\bar{q}}$.
double qWeightX (Energy qtilde, double z)
 Soft quark weight calculated from $\tilde{q},z$.
double qbarWeightX (Energy qtilde, double z)
 Soft antiquark weight calculated from $\tilde{q},z$.
double MEV (double, double)
 Vector and axial vector parts of the matrix element.
double MEA (double, double)
 Axial vector part of the matrix element.
double PS (double x1, double x2)
 The matrix element, given $x_1$, $x_2$.

Private Attributes

AbstractFFVVertexPtr FFZVertex_
 Pointer to the fermion-antifermion Z vertex.
AbstractFFVVertexPtr FFPVertex_
 Pointer to the fermion-antifermion photon vertex.
AbstractFFVVertexPtr FFGVertex_
 Pointer to the fermion-antifermion photon vertex.
PDPtr Z0_
 Pointer to the particle data object for the Z.
PDPtr gamma_
 Pointer to the particle data object for the photon.
PDPtr gluon_
 Pointer to the particle data object for the gluon.
int minflav_
 The minimum PDG of the quarks to be produced.
int maxflav_
 The maximum PDG of the quarks to be produced.
unsigned int massopt_
 Option for the treatment of the top quark mass.
Energy d_Q_
 CM energy.
Energy d_m_
 Quark mass.
double d_rho_
 The rho parameter.
double d_v_
 The v parameter.
double d_kt1_
 The initial kappa-tilde values for radiation from the quark.
double d_kt2_
 The initial kappa-tilde values for radiation from the antiquark.
ShowerAlphaPtr alpha_
 Pointer to the coupling.
Energy pTmin_
 Variables for the POWHEG style corrections.
double preFactor_
 Overestimate for the prefactor.
vector< cPDPtrpartons_
 ParticleData objects for the partons.
vector< Lorentz5Momentum > loMomenta_
 Momenta of the leading-order partons.

Static Private Attributes

static ClassDescription
< MEee2gZ2qq
initMEee2gZ2qq
 The static object used to initialize the description of this class.
static const double EPS_
 Cut-off parameter.

Detailed Description

The MEee2gZ2qq class implements the matrix element for $e^+e^-\to Z/\gamma \to q\bar{q}$ including spin correlations.

The class includes greater control over the type of quark produced than is available in the corresponding matrix element from ThePEG, in addition to spin correlations.

See also:
The interfaces defined for MEee2gZ2qq.

Definition at line 38 of file MEee2gZ2qq.h.


Member Function Documentation

virtual IBPtr Herwig::MEee2gZ2qq::clone ( ) const [inline, protected, virtual]

Make a simple clone of this object.

Returns:
a pointer to the new object.

Implements ThePEG::InterfacedBase.

Definition at line 186 of file MEee2gZ2qq.h.

virtual Selector<const ColourLines *> Herwig::MEee2gZ2qq::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::MEee2gZ2qq::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::MEee2gZ2qq::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::MEee2gZ2qq::fullclone ( ) const [inline, 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.

Definition at line 192 of file MEee2gZ2qq.h.

virtual IVector Herwig::MEee2gZ2qq::getReferences ( ) [protected, virtual]

Return a vector of all pointers to Interfaced objects used in this object.

Returns:
a vector of pointers.

Reimplemented from ThePEG::InterfacedBase.

void Herwig::MEee2gZ2qq::getXXbar ( double  kt,
double  z,
double &  x,
double &  xbar 
) [private]

Calculate $x_{q},x_{\bar{q}}$ from $\tilde{\kappa},z$.

Parameters:
kt$\tilde{\kappa}$
z$z$
x$x_{q}$
xbar$x_{\bar{q}}$
double Herwig::MEee2gZ2qq::getZfromX ( double  ,
double   
) [private]

Translate the variables from $x_q,x_{\bar{q}}$ to $\tilde{\kappa},z$.

Calculate $z$.

virtual POWHEGType Herwig::MEee2gZ2qq::hasPOWHEGCorrection ( ) [inline, virtual]

Members for hard corrections to the emission of QCD radiation.

Has a POWHEG style correction

Reimplemented from Herwig::HwMEBase.

Definition at line 56 of file MEee2gZ2qq.h.

ProductionMatrixElement Herwig::MEee2gZ2qq::HelicityME ( vector< SpinorWaveFunction > &  fin,
vector< SpinorBarWaveFunction > &  ain,
vector< SpinorBarWaveFunction > &  fout,
vector< SpinorWaveFunction > &  aout,
double &  me,
double &  cont,
double &  BW 
) const [protected]

Member to calculate the matrix element.

Parameters:
finSpinors for incoming fermion
ainSpinors for incoming antifermion
foutSpinors for outgoing fermion
aoutSpinors for outgong antifermion
meSpin summed Matrix element
contThe continuum piece of the matrix element
BWThe Z piece of the matrix element
static void Herwig::MEee2gZ2qq::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.

double Herwig::MEee2gZ2qq::loME ( const vector< cPDPtr > &  partons,
const vector< Lorentz5Momentum > &  momenta,
bool  first 
) const [protected]

Calculate the matrix element for $e^-e^-\to q \bar q$.

Parameters:
partonsThe incoming and outgoing particles
momentaThe momenta of the incoming and outgoing particles
firstWhether or not to calculate the spin correlations
virtual double Herwig::MEee2gZ2qq::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.

double Herwig::MEee2gZ2qq::meRatio ( vector< cPDPtr partons,
vector< Lorentz5Momentum >  momenta,
unsigned int  iemitter,
bool  subtract = false 
) const [protected]

The ratio of the matrix element for one additional jet over the leading order result.

In practice

\[\frac{\hat{s}|\overline{\mathcal{M}}|^2_2|D_{\rm emit}|}{4\pi C_F\alpha_S|\overline{\mathcal{M}}|^2_3\left(|D_{\rm emit}|+|D_{\rm spect}|\right)}\]

is returned where $\|\overline{\mathcal{M}}|^2$ is the spin and colour summed/averaged matrix element.

Parameters:
partonsThe incoming and outgoing particles
momentaThe momenta of the incoming and outgoing particles
iemitterWhether the quark or antiquark is regardede as the emitter
subtractWhether or not to subtract the relevant dipole term
double Herwig::MEee2gZ2qq::MEV ( double  ,
double   
) [private]

Vector and axial vector parts of the matrix element.

Vector part of the matrix element

MEee2gZ2qq& Herwig::MEee2gZ2qq::operator= ( const MEee2gZ2qq ) [private]

The assignment operator is private and must never be called.

In fact, it should not even be implemented.

void Herwig::MEee2gZ2qq::persistentInput ( PersistentIStream is,
int  version 
)

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::MEee2gZ2qq::PS ( double  x1,
double  x2 
) [private]

The matrix element, given $x_1$, $x_2$.

Parameters:
x1$x_1$
x2$x_2$
double Herwig::MEee2gZ2qq::qbarWeight ( double  x,
double  xbar 
) [private]

Soft antiquark weight calculated from $x_{q},x_{\bar{q}}$.

Parameters:
x$x_{q}$
xbar$x_{\bar{q}}$
double Herwig::MEee2gZ2qq::qbarWeightX ( Energy  qtilde,
double  z 
) [private]

Soft antiquark weight calculated from $\tilde{q},z$.

Parameters:
qtilde$\tilde{q}$
z$z$
double Herwig::MEee2gZ2qq::qWeight ( double  x,
double  xbar 
) [private]

Soft weight.

Soft quark weight calculated from $x_{q},x_{\bar{q}}$

Parameters:
x$x_{q}$
xbar$x_{\bar{q}}$
double Herwig::MEee2gZ2qq::qWeightX ( Energy  qtilde,
double  z 
) [private]

Soft quark weight calculated from $\tilde{q},z$.

Parameters:
qtilde$\tilde{q}$
z$z$
InvEnergy2 Herwig::MEee2gZ2qq::realME ( const vector< cPDPtr > &  partons,
const vector< Lorentz5Momentum > &  momenta 
) const [protected]

Calculate the matrix element for $e^-e^-\to q \bar q g$.

Parameters:
partonsThe incoming and outgoing particles
momentaThe momenta of the incoming and outgoing particles
virtual void Herwig::MEee2gZ2qq::rebind ( const TranslationMap trans) [protected, virtual]

Rebind pointer to other Interfaced objects.

Called in the setup phase after all objects used in an EventGenerator has been cloned so that the pointers will refer to the cloned objects afterwards.

Parameters:
transa TranslationMap relating the original objects to their respective clones.
Exceptions:
RebindExceptionif no cloned object was found for a given pointer.

Reimplemented from ThePEG::InterfacedBase.

virtual bool Herwig::MEee2gZ2qq::softMatrixElementVeto ( ShowerProgenitorPtr  initial,
ShowerParticlePtr  parent,
Branching  br 
) [virtual]

Apply the soft matrix element correction.

Parameters:
initialThe particle from the hard process which started the shower
parentThe initial particle in the current branching
brThe branching struct
Returns:
If true the emission should be vetoed

Reimplemented from Herwig::HwMEBase.


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 424 of file MEee2gZ2qq.h.

Energy Herwig::MEee2gZ2qq::pTmin_ [private]

Variables for the POWHEG style corrections.

The cut off on pt, assuming massless quarks.

Definition at line 528 of file MEee2gZ2qq.h.


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