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Herwig  7.1.4
Herwig::SudakovFormFactor Class Referenceabstract

This is the definition of the Sudakov form factor class. More...

#include <SudakovFormFactor.h>

Inheritance diagram for Herwig::SudakovFormFactor:

Public Member Functions

 SudakovFormFactor ()
 The default constructor.
 
virtual double generatePhiForward (ShowerParticle &particle, const IdList &ids, ShoKinPtr kinematics, const RhoDMatrix &rho)=0
 Generate the azimuthal angle of the branching for forward evolution. More...
 
virtual double generatePhiBackward (ShowerParticle &particle, const IdList &ids, ShoKinPtr kinematics, const RhoDMatrix &rho)=0
 Generate the azimuthal angle of the branching for backward evolution. More...
 
virtual double generatePhiDecay (ShowerParticle &particle, const IdList &ids, ShoKinPtr kinematics, const RhoDMatrix &rho)=0
 Generate the azimuthal angle of the branching for ISR in decays. More...
 
double pdfMax () const
 Access the maximum weight for the PDF veto.
 
virtual Energy calculateScale (double z, Energy pt, IdList ids, unsigned int iopt)=0
 Method to return the evolution scale given the transverse momentum, $p_T$ and $z$.
 
virtual ShoKinPtr createFinalStateBranching (Energy scale, double z, double phi, Energy pt)=0
 Method to create the ShowerKinematics object for a final-state branching.
 
virtual ShoKinPtr createInitialStateBranching (Energy scale, double z, double phi, Energy pt)=0
 Method to create the ShowerKinematics object for an initial-state branching.
 
virtual ShoKinPtr createDecayBranching (Energy scale, double z, double phi, Energy pt)=0
 Method to create the ShowerKinematics object for a decay branching.
 
void setPDF (tcPDFPtr pdf, Energy scale)
 Set the PDF.
 
virtual ShoKinPtr generateNextTimeBranching (const Energy startingScale, const IdList &ids, const RhoDMatrix &rho, double enhance, double detuning, Energy2 maxQ2)=0
 Members to generate the scale of the next branching. More...
 
virtual ShoKinPtr generateNextDecayBranching (const Energy startingScale, const Energy stoppingScale, const Energy minmass, const IdList &ids, const RhoDMatrix &rho, double enhance, double detuning)=0
 Return the scale of the next space-like decay branching. More...
 
virtual ShoKinPtr generateNextSpaceBranching (const Energy startingScale, const IdList &ids, double x, const RhoDMatrix &rho, double enhance, tcBeamPtr beam, double detuning)=0
 Return the scale of the next space-like branching. More...
 
tSplittingFnPtr splittingFn () const
 Methods to provide public access to the private member variables. More...
 
tShowerAlphaPtr alpha () const
 Return the pointer to the ShowerAlpha object.
 
ShowerInteraction interactionType () const
 The type of interaction.
 
double z () const
 Methods to access the kinematic variables for the branching. More...
 
double phi () const
 The azimuthal angle.
 
Energy pT () const
 The transverse momentum.
 
Functions used by the persistent I/O system.
void persistentOutput (PersistentOStream &os) const
 Function used to write out object persistently. More...
 
void persistentInput (PersistentIStream &is, int version)
 Function used to read in object persistently. More...
 
Methods for the cut-off
unsigned int cutOffOption () const
 The option being used.
 
Energy kinScale () const
 The kinematic scale.
 
Energy kinematicCutOff (Energy scale, Energy mq) const
 The virtuality cut-off on the gluon $Q_g=\frac{\delta-am_q}{b}$. More...
 
Energy vgCut () const
 The virtualilty cut-off for gluons.
 
Energy vqCut () const
 The virtuality cut-off for everything else.
 
Energy pTmin () const
 The minimum $p_T$ for the branching.
 
Energy2 pT2min () const
 The square of the minimum $p_T$.
 
const vector< Energy > & virtualMasses (const IdList &ids)
 Calculate the virtual masses for a branchings.
 
- 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
 
void persistentOutput (PersistentOStream &os) const
 
void persistentInput (PersistentIStream &is, int version)
 
- Public Member Functions inherited from ThePEG::InterfacedBase
string fullName () const
 
string name () const
 
string path () const
 
string comment () const
 
void setup (istream &is)
 
virtual IBPtr fullclone () const
 
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
 
void persistentOutput (PersistentOStream &os) const
 
void persistentInput (PersistentIStream &is, int version)
 
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
 
void persistentOutput (PersistentOStream &os) const
 
void persistentInput (PersistentIStream &is, int version)
 
- Public Member Functions inherited from ThePEG::Base
void debug () const
 
- Public Member Functions inherited from ThePEG::Pointer::ReferenceCounted
CounterType referenceCount () const
 
- Public Member Functions inherited from ThePEG::Named
 Named (const string &newName=string())
 
const string & name () const
 
bool operator== (const Named &other) const
 
bool operator< (const Named &other) const
 

Static Public Member Functions

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

Protected Member Functions

void addSplitting (const IdList &)
 Set the particles in the splittings.
 
void removeSplitting (const IdList &)
 Delete the particles in the splittings.
 
const vector< IdList > & particles () const
 Access the potential branchings.
 
Standard Interfaced functions.
virtual void doinit ()
 Initialize this object after the setup phase before saving an EventGenerator to disk. More...
 
double guessz (unsigned int iopt, const IdList &ids) const
 Methods to implement the veto algorithm to generate the scale of the next branching. More...
 
Energy2 guesst (Energy2 t1, unsigned int iopt, const IdList &ids, double enhance, bool identical, double detune) const
 Value of the scale for the veto algorithm. More...
 
bool PDFVeto (const Energy2 t, const double x, const tcPDPtr parton0, const tcPDPtr parton1, tcBeamPtr beam) const
 Veto on the PDF for the initial-state shower. More...
 
double PDFVetoRatio (const Energy2 t, const double x, const tcPDPtr parton0, const tcPDPtr parton1, tcBeamPtr beam, double factor) const
 The PDF veto ratio.
 
bool SplittingFnVeto (const Energy2 t, const IdList &ids, const bool mass, const RhoDMatrix &rho, double detune) const
 The veto on the splitting function. More...
 
double SplittingFnVetoRatio (const Energy2 t, const IdList &ids, const bool mass, const RhoDMatrix &rho, double detune) const
 The Splitting function veto ratio.
 
bool alphaSVeto (Energy2 pt2) const
 The veto on the coupling constant. More...
 
double alphaSVetoRatio (Energy2 pt2, double factor) const
 The alpha S veto ratio.
 
void z (double in)
 Methods to set the kinematic variables for the branching. More...
 
void phi (double in)
 The azimuthal angle.
 
void pT (Energy in)
 The transverse momentum.
 
pair< double, double > zLimits () const
 Set/Get the limits on the energy fraction for the splitting. More...
 
void zLimits (pair< double, double > in)
 Set the limits.
 
- 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 IBPtr clone () const=0
 
 InterfacedBase (string newName)
 
 InterfacedBase (const InterfacedBase &i)
 
virtual void readSetup (istream &is)
 
virtual void doupdate ()
 
virtual void doinitrun ()
 
virtual void dofinish ()
 
virtual IVector getReferences ()
 
virtual void rebind (const TranslationMap &)
 
virtual void readSetup (istream &is)
 
virtual void doupdate ()
 
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 &)
 
ReferenceCountedoperator= (const ReferenceCounted &)
 
 ReferenceCounted (const ReferenceCounted &)
 
ReferenceCountedoperator= (const ReferenceCounted &)
 
- Protected Member Functions inherited from ThePEG::Named
const Namedoperator= (const Named &other)
 
const string & name (const string &newName)
 

Private Member Functions

SudakovFormFactoroperator= (const SudakovFormFactor &)
 The assignment operator is private and must never be called. More...
 

Private Attributes

SplittingFnPtr splittingFn_
 Pointer to the splitting function for this Sudakov form factor.
 
ShowerAlphaPtr alpha_
 Pointer to the coupling for this Sudakov form factor.
 
double pdfmax_
 Maximum value of the PDF weight.
 
vector< IdListparticles_
 List of the particles this Sudakov is used for to aid in setting up interpolation tables if needed.
 
unsigned pdffactor_
 Option for the inclusion of a factor $1/(1-z)$ in the PDF estimate.
 
unsigned int cutOffOption_
 Option for the type of cut-off to be applied.
 
pair< double, double > zlimits_
 The limits of $z$ in the splitting.
 
double a_
 Parameters for the default Herwig cut-off option, i.e. More...
 
double b_
 The $b$ parameter.
 
Energy c_
 The $c$ parameter.
 
Energy kinCutoffScale_
 Kinematic cutoff used in the parton shower phase space.
 
Energy vgcut_
 Parameters for the FORTRAN-like cut-off. More...
 
Energy vqcut_
 The virtuality cut-off for everything else.
 
Energy pTmin_
 Parameters for the $p_T$ cut-off. More...
 
Energy2 pT2min_
 The square of the minimum $p_T$.
 
double z_
 Member variables to keep the shower kinematics information generated by a call to generateNextTimeBranching or generateNextSpaceBranching. More...
 
double phi_
 The azimuthal angle.
 
Energy pT_
 The transverse momentum.
 
tcPDFPtr pdf_
 Stuff for the PDFs. More...
 
Energy freeze_
 Freezing scale.
 

Friends

class SplittingGenerator
 The SplittingGenerator is a friend to insert the particles in the branchings at initialisation.
 

Additional Inherited Members

- Public Types inherited from ThePEG::InterfacedBase
enum  InitState
 
- Public Types inherited from ThePEG::Pointer::ReferenceCounted
typedef unsigned int CounterType
 
- 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

This is the definition of the Sudakov form factor class.

In general this is the base class for the implementation of Sudakov form factors in Herwig. The methods generateNextTimeBranching(), generateNextDecayBranching() and generateNextSpaceBranching need to be implemented in classes inheriting from this one.

In addition a number of methods are implemented to assist with the calculation of the form factor using the veto algorithm in classes inheriting from this one.

In general the Sudakov form-factor, for final-state radiation, is given by

\[\Delta_{ba}(\tilde{q}_{i+1},\tilde{q}_i)= \exp\left\{ -\int^{\tilde{q}^2_i}_{\tilde{q}^2_{i+1}} \frac{{\rm d}\tilde{q}^2}{\tilde{q}^2} \int\frac{\alpha_S(z,\tilde{q})}{2\pi} P_{ba}(z,\tilde{q})\Theta(p_T) \right\}. \]

We can solve this to obtain the next value of the scale $\tilde{q}_{i+1}$ given the previous value $\tilde{q}_i$ in the following way. First we obtain a simplified form of the integrand which is greater than or equal to the true integrand for all values of $\tilde{q}$.

In practice it is easiest to obtain this over estimate in pieces. The ShowerAlpha object contains an over estimate for $\alpha_S$, the splitting function contains both an over estimate of the spltting function and its integral which is needed to compute the over estimate of the $\tilde{q}$ integrand, together with an over estimate of the limit of the $z$ integral.

This gives an overestimate of the integrand

\[g(\tilde{q}^2) = \frac{c}{\tilde{q}^2}, \]

where because the over estimates are chosen to be independent of $\tilde{q}$ the parameter

\[c = \frac{\alpha_{\rm over}}{2\pi}\int^{z_1}_{z_0}P_{\rm over}(z),\]

is a constant independent of $\tilde{q}$.

The guesst() member can then be used to generate generate the value of $\tilde{q}^2$ according to this result. This is done by solving the Sudakov form factor, with the over estimates, is equal to a random number $r$ in the interval $[0,1]$. This gives

\[\tilde{q}^2_{i+1}=G^{-1}\left[G(\tilde{q}^2_i)+\ln r\right],\]

where $G(\tilde{q}^2)=c\ln(\tilde{q}^2)$ is the infinite integral of $g(\tilde{q}^2)$ and $G^{-1}(x)=\exp\left(\frac{x}c\right)$ is its inverse. It this case we therefore obtain

\[\tilde{q}^2_{i+1}=\tilde{q}^2_ir^{\frac1c}.\]

The value of $z$ can then be calculated in a similar way

\[z = I^{-1}\left[I(z_0)+r\left(I(z_1)-I(z_0)\right)\right],\]

using the guessz() member, where $I=\int P(z){\rm d}z$ and $I^{-1}$ is its inverse.

The veto algorithm then uses rejection using the ratio of the true value to the overestimated one to obtain the original distribution. This is accomplished using the

  • alphaSVeto() member for the $\alpha_S$ veto
  • SplittingFnVeto() member for the veto on the value of the splitting function. in general there must also be a chech that the emission is in the allowed phase space but this is left to the inheriting classes as it will depend on the ordering variable.

The Sudakov form factor for the initial-scale shower is different because it must include the PDF which guides the backward evolution. It is given by

\[\Delta_{ba}(\tilde{q}_{i+1},\tilde{q}_i)= \exp\left\{ -\int^{\tilde{q}^2_i}_{\tilde{q}^2_{i+1}} \frac{{\rm d}\tilde{q}^2}{\tilde{q}^2} \int\frac{\alpha_S(z,\tilde{q})}{2\pi} P_{ba}(z,\tilde{q})\frac{x'f_a(\frac{x}z,\tilde{q}^2)}{xf_b(x,\tilde{q^2})} \right\}, \]

where $x$ is the fraction of the beam momentum the parton $b$ had before the backward evolution. This can be solve in the same way as for the final-state branching but the constant becomes

\[c = \frac{\alpha_{\rm over}}{2\pi}\int^{z_1}_{z_0}P_{\rm over}(z)PDF_{\rm max},\]

where

\[PDF_{\rm max}=\max\frac{x'f_a(\frac{x}z,\tilde{q}^2)}{xf_b(x,\tilde{q^2})},\]

which can be set using an interface. In addition the PDFVeto() member then is needed to implement the relevant veto.

See also
SplittingGenerator
SplittingFunction
ShowerAlpha
The interfaces defined for SudakovFormFactor.

Definition at line 126 of file SudakovFormFactor.h.

Member Function Documentation

◆ alphaSVeto()

bool Herwig::SudakovFormFactor::alphaSVeto ( Energy2  pt2) const
protected

The veto on the coupling constant.

Parameters
pt2The value of ther transverse momentum squared, $p_T^2$.
Returns
true if vetoed

◆ doinit()

virtual void Herwig::SudakovFormFactor::doinit ( )
protectedvirtual

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.

◆ generateNextDecayBranching()

virtual ShoKinPtr Herwig::SudakovFormFactor::generateNextDecayBranching ( const Energy  startingScale,
const Energy  stoppingScale,
const Energy  minmass,
const IdList ids,
const RhoDMatrix rho,
double  enhance,
double  detuning 
)
pure virtual

Return the scale of the next space-like decay branching.

If there is no branching then it returns ZERO.

Parameters
startingScalestarting scale for the evolution
stoppingScalestopping scale for the evolution
minmassThe minimum mass allowed for the spake-like particle.
idsThe PDG codes of the particles in the splitting defined.
enhanceThe radiation enhancement factor

Implemented in Herwig::QTildeSudakov.

◆ generateNextSpaceBranching()

virtual ShoKinPtr Herwig::SudakovFormFactor::generateNextSpaceBranching ( const Energy  startingScale,
const IdList ids,
double  x,
const RhoDMatrix rho,
double  enhance,
tcBeamPtr  beam,
double  detuning 
)
pure virtual

Return the scale of the next space-like branching.

If there is no branching then it returns ZERO.

Parameters
startingScalestarting scale for the evolution
idsThe PDG codes of the particles in the splitting
xThe fraction of the beam momentum defined.
beamThe beam particle
enhanceThe radiation enhancement factor

Implemented in Herwig::QTildeSudakov.

◆ generateNextTimeBranching()

virtual ShoKinPtr Herwig::SudakovFormFactor::generateNextTimeBranching ( const Energy  startingScale,
const IdList ids,
const RhoDMatrix rho,
double  enhance,
double  detuning,
Energy2  maxQ2 
)
pure virtual

Members to generate the scale of the next branching.

Return the scale of the next time-like branching. If there is no branching then it returns ZERO.

Parameters
startingScalestarting scale for the evolution
idsThe PDG codes of the particles in the splitting
enhanceThe radiation enhancement factor defined.

Implemented in Herwig::QTildeSudakov.

◆ generatePhiBackward()

virtual double Herwig::SudakovFormFactor::generatePhiBackward ( ShowerParticle particle,
const IdList ids,
ShoKinPtr  kinematics,
const RhoDMatrix rho 
)
pure virtual

Generate the azimuthal angle of the branching for backward evolution.

Parameters
particleThe branching particle
idsThe PDG codes of the particles in the branchings
TheShower kinematics

Implemented in Herwig::QTildeSudakov.

◆ generatePhiDecay()

virtual double Herwig::SudakovFormFactor::generatePhiDecay ( ShowerParticle particle,
const IdList ids,
ShoKinPtr  kinematics,
const RhoDMatrix rho 
)
pure virtual

Generate the azimuthal angle of the branching for ISR in decays.

Parameters
particleThe branching particle
idsThe PDG codes of the particles in the branchings
TheShower kinematics

Implemented in Herwig::QTildeSudakov.

◆ generatePhiForward()

virtual double Herwig::SudakovFormFactor::generatePhiForward ( ShowerParticle particle,
const IdList ids,
ShoKinPtr  kinematics,
const RhoDMatrix rho 
)
pure virtual

Generate the azimuthal angle of the branching for forward evolution.

Parameters
particleThe branching particle
idsThe PDG codes of the particles in the branchings
TheShower kinematics

Implemented in Herwig::QTildeSudakov.

◆ guesst()

Energy2 Herwig::SudakovFormFactor::guesst ( Energy2  t1,
unsigned int  iopt,
const IdList ids,
double  enhance,
bool  identical,
double  detune 
) const
protected

Value of the scale for the veto algorithm.

Parameters
t1The starting valoe of the scale
ioptThe option for calculating t
idsThe PDG codes of the particles in the splitting
  • 0 is final-state
  • 1 is initial-state for the hard process
  • 2 is initial-state for particle decays
enhanceThe radiation enhancement factor
identicalWhether or not the outgoing particles are identical

◆ guessz()

double Herwig::SudakovFormFactor::guessz ( unsigned int  iopt,
const IdList ids 
) const
protected

Methods to implement the veto algorithm to generate the scale of the next branching.

Value of the energy fraction for the veto algorithm

Parameters
ioptThe option for calculating z
idsThe PDG codes of the particles in the splitting
  • 0 is final-state
  • 1 is initial-state for the hard process
  • 2 is initial-state for particle decays

◆ Init()

static void Herwig::SudakovFormFactor::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.

◆ kinematicCutOff()

Energy Herwig::SudakovFormFactor::kinematicCutOff ( Energy  scale,
Energy  mq 
) const
inline

The virtuality cut-off on the gluon $Q_g=\frac{\delta-am_q}{b}$.

Parameters
scaleThe scale $\delta$
mqThe quark mass $m_q$.

Definition at line 504 of file SudakovFormFactor.h.

◆ operator=()

SudakovFormFactor& Herwig::SudakovFormFactor::operator= ( const SudakovFormFactor )
private

The assignment operator is private and must never be called.

In fact, it should not even be implemented.

◆ PDFVeto()

bool Herwig::SudakovFormFactor::PDFVeto ( const Energy2  t,
const double  x,
const tcPDPtr  parton0,
const tcPDPtr  parton1,
tcBeamPtr  beam 
) const
protected

Veto on the PDF for the initial-state shower.

Parameters
tThe scale
xThe fraction of the beam momentum
parton0Pointer to the particleData for the new parent (this is the particle we evolved back to)
parton1Pointer to the particleData for the original particle
beamThe BeamParticleData object

◆ persistentInput()

void Herwig::SudakovFormFactor::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.

◆ persistentOutput()

void Herwig::SudakovFormFactor::persistentOutput ( PersistentOStream os) const

Function used to write out object persistently.

Parameters
osthe persistent output stream written to.

◆ splittingFn()

tSplittingFnPtr Herwig::SudakovFormFactor::splittingFn ( ) const
inline

Methods to provide public access to the private member variables.

Return the pointer to the SplittingFunction object.

Definition at line 236 of file SudakovFormFactor.h.

◆ SplittingFnVeto()

bool Herwig::SudakovFormFactor::SplittingFnVeto ( const Energy2  t,
const IdList ids,
const bool  mass,
const RhoDMatrix rho,
double  detune 
) const
inlineprotected

The veto on the splitting function.

Parameters
tThe scale
idsThe PDG codes of the particles in the splitting
massWhether or not to use the massive splitting functions
Returns
true if vetoed

Definition at line 397 of file SudakovFormFactor.h.

References ThePEG::UseRandom::rnd().

◆ z() [1/2]

double Herwig::SudakovFormFactor::z ( ) const
inline

Methods to access the kinematic variables for the branching.

The energy fraction

Definition at line 259 of file SudakovFormFactor.h.

◆ z() [2/2]

void Herwig::SudakovFormFactor::z ( double  in)
inlineprotected

Methods to set the kinematic variables for the branching.

The energy fraction

Definition at line 440 of file SudakovFormFactor.h.

◆ zLimits()

pair<double,double> Herwig::SudakovFormFactor::zLimits ( ) const
inlineprotected

Set/Get the limits on the energy fraction for the splitting.

Get the limits

Definition at line 460 of file SudakovFormFactor.h.

Member Data Documentation

◆ a_

double Herwig::SudakovFormFactor::a_
private

Parameters for the default Herwig cut-off option, i.e.

the parameters for the $Q_g=\max(\frac{\delta-am_q}{b},c)$ kinematic cut-off The $a$ parameter

Definition at line 592 of file SudakovFormFactor.h.

◆ pdf_

tcPDFPtr Herwig::SudakovFormFactor::pdf_
private

Stuff for the PDFs.

PDf

Definition at line 675 of file SudakovFormFactor.h.

◆ pTmin_

Energy Herwig::SudakovFormFactor::pTmin_
private

Parameters for the $p_T$ cut-off.

The minimum $p_T$ for the branching

Definition at line 632 of file SudakovFormFactor.h.

◆ vgcut_

Energy Herwig::SudakovFormFactor::vgcut_
private

Parameters for the FORTRAN-like cut-off.

The virtualilty cut-off for gluons

Definition at line 617 of file SudakovFormFactor.h.

◆ z_

double Herwig::SudakovFormFactor::z_
private

Member variables to keep the shower kinematics information generated by a call to generateNextTimeBranching or generateNextSpaceBranching.

The energy fraction

Definition at line 650 of file SudakovFormFactor.h.


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