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Herwig 7.3.0
Herwig::EtaPiGammaGammaDecayer Class Reference

The EtaPiGammaGammaDecayer class implements a VMD model matrix element for \(\eta,\eta'\to \pi^0 \gamma \gamma\) taken from hep-ph/0112150. More...

#include <EtaPiGammaGammaDecayer.h>

Inheritance diagram for Herwig::EtaPiGammaGammaDecayer:

Public Member Functions

 EtaPiGammaGammaDecayer ()
 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.
 
virtual WidthCalculatorBasePtr threeBodyMEIntegrator (const DecayMode &dm) const
 Method to return an object to calculate the 3 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 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 StandardModelBaseSM () 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 &)
 
ReferenceCountedoperator= (const ReferenceCounted &)
 
- Protected Member Functions inherited from ThePEG::Named
const Namedoperator= (const Named &other)
 
const string & name (const string &newName)
 

Standard Interfaced functions.

InvEnergy _grhoomega
 The coupling \(g_{\omega\rho\pi}\) of the \(\rho\) to \(\omega\) and a \(\pi\).
 
Energy _fpi
 The pion decay constant, \(F_{\pi}\).
 
Energy _rhomass
 The mass of the \(\rho\).
 
Energy _rhowidth
 The width of the \(\rho\).
 
double _grho
 The coupling for the conversion of a rho to a photon, \(g\).
 
Energy _mpi
 The mass of the pion.
 
double _rhoconst
 Constant for the running \(\rho\) width calculation.
 
bool _localparameters
 Use local values of the \(\rho\) mass and width.
 
double _ratiofpif8
 Ratios of the decay constants \(F_8/F_\pi\).
 
double _ratiofpif0
 Ratios of the decay constants \(F_0/F_\pi\).
 
double _theta
 the mixing angle, \(\theta\).
 
double _etamax
 the maximum weights for the \(\eta\) decay.
 
double _etapmax
 the maximum weights for the \(\eta'\) decay.
 
vector< InvEnergy2 > _dconst
 The prefactor for the \(D(s,t,u)\) function.
 
vector< InvEnergy2 > _econst
 The prefactor for the \(E(s,t,u)\) function.
 
RhoDMatrix _rho
 Spin density matrix.
 
vector< Helicity::LorentzPolarizationVector_vectors [2]
 Polarization vectors for the photons.
 
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.
 
EtaPiGammaGammaDecayeroperator= (const EtaPiGammaGammaDecayer &)=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 EtaPiGammaGammaDecayer class implements a VMD model matrix element for \(\eta,\eta'\to \pi^0 \gamma \gamma\) taken from hep-ph/0112150.

The matrix element is given by

\[ \mathcal{M} = D(s,t,u)\left[ \epsilon_1\cdot\epsilon_2 q_1\cdot q_2 -\epsilon_1\cdot q_2\epsilon_2\cdot q_1\right] -E(s,t,u)\left[-\epsilon_1\cdot\epsilon_2p\cdot q_1p\cdot q_2 -\epsilon_1\cdot p\epsilon_2\cdot p q_1\cdot q_2 +\epsilon_1\cdot q_2 \epsilon_2\cdot p p\cdot q_1 +\epsilon_1\cdot p \epsilon_2\cdot q_1 p\cdot q_2 *\right], \]

where \(q_{1,2}\) are the momenta of the photons, \(\epsilon_{1,2}\) are the polarization vectors of the photons, \(p\) is the momentum of the decaying meson and

\[D(s,t,u) = \frac{2\sqrt{3}}{9}g^2_{\omega\rho\pi} \left(\frac{2eF^2_{\pi}g}{m^2_V}\right)^2\times\left(\frac{F_\pi}{F_8}\cos\theta\mp\sqrt{2}\frac{F_\pi}{F_0}\sin\theta\right)\times\left[\frac{p\cdot q_2-m^2_\eta}{m^2_V-t}+\frac{p\cdot q_1-m^2_\eta}{m^2_V-u}\right]\]

\[E(s,t,u) =-\frac{2\sqrt{3}}{9}g^2_{\omega\rho\pi}\left(\frac{2eF^2_{\pi}g}{m^2_V}\right)^2\times\left(\frac{F_\pi}{F_8}\cos\theta\mp\sqrt{2}\frac{F_\pi}{F_0}\sin\theta\right)\times\left[\frac1{m^2_V-t}+\frac1{m^2_V-u}\right].\]

the \(-\) sign corresponds to the \(\eta\) decay and the \(+\) to the \(\eta'\) decay. Here

  • \(g_{\omega\rho\pi}\) is the coupling of the \(\omega\) to the \(\rho\) and a pion.
  • \(e\) is the electric charge.
  • \(F_{\pi}\) is the pion decay constant.
  • \(g\) is the conversion factor for a \(\rho\) into a photon.
  • \(m_V\) is the mass of the vector meson, in this case we use the \(\rho\).
  • \(F_0\) is the singlet decay constant.
  • \(F_8\) is the octet decay constant.
  • \(\theta\) is the octet-singlet mixing angle
  • \(m_\eta\) is the mass of the decay meson.

    In practice we use a slightly modified form by including a running width term to include the \(\eta'\) decay as well as the \(\eta\) decay.

See also
DecayIntegrator

Definition at line 63 of file EtaPiGammaGammaDecayer.h.

Member Function Documentation

◆ clone()

virtual IBPtr Herwig::EtaPiGammaGammaDecayer::clone ( ) const
inlineprotectedvirtual

Make a simple clone of this object.

Returns
a pointer to the new object.

Implements ThePEG::InterfacedBase.

Definition at line 164 of file EtaPiGammaGammaDecayer.h.

◆ constructSpinInfo()

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

Output the setup information for the particle database.

Parameters
osThe stream to output the information to
headerWhether or not to output the information for MySQL

Reimplemented from Herwig::DecayIntegrator.

◆ doinit()

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

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

Exceptions
InitExceptionif object could not be initialized properly.

Reimplemented from ThePEG::InterfacedBase.

◆ doinitrun()

virtual void Herwig::EtaPiGammaGammaDecayer::doinitrun ( )
protectedvirtual

Initialize this object to the begining of the run phase.

Reimplemented from Herwig::DecayIntegrator.

◆ fullclone()

virtual IBPtr Herwig::EtaPiGammaGammaDecayer::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 170 of file EtaPiGammaGammaDecayer.h.

◆ me2()

double Herwig::EtaPiGammaGammaDecayer::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
ichanThe channel we are calculating the matrix element for.
partThe decaying Particle.
outgoingThe particles produced in the decay
momentaThe momenta of the particles produced in the decay
meoptOption for the calculation of the matrix element
Returns
The matrix element squared for the phase-space configuration.

Implements Herwig::DecayIntegrator.

◆ modeNumber()

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

Which of the possible decays is required.

Parameters
ccIs this mode the charge conjugate
parentThe decaying particle
childrenThe decay products

Implements Herwig::DecayIntegrator.

◆ persistentInput()

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

Function used to write out object persistently.

Parameters
osthe persistent output stream written to.

◆ threeBodyMatrixElement()

virtual double Herwig::EtaPiGammaGammaDecayer::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
virtual

The matrix element to be integrated for the three-body decays as a function of the invariant masses of pairs of the outgoing particles.

Parameters
imodeThe mode for which the matrix element is needed.
q2The scale, i.e. the mass squared of the decaying particle.
s3The invariant mass squared of particles 1 and 2, \(s_3=m^2_{12}\).
s2The invariant mass squared of particles 1 and 3, \(s_2=m^2_{13}\).
s1The invariant mass squared of particles 2 and 3, \(s_1=m^2_{23}\).
m1The mass of the first outgoing particle.
m2The mass of the second outgoing particle.
m3The mass of the third outgoing particle.
Returns
The matrix element

Reimplemented from Herwig::DecayIntegrator.

◆ threeBodyMEIntegrator()

virtual WidthCalculatorBasePtr Herwig::EtaPiGammaGammaDecayer::threeBodyMEIntegrator ( const DecayMode dm) const
virtual

Method to return an object to calculate the 3 body partial width.

Parameters
dmThe DecayMode
Returns
A pointer to a WidthCalculatorBase object capable of calculating the width

Reimplemented from Herwig::DecayIntegrator.

Member Data Documentation

◆ _dconst

vector<InvEnergy2> Herwig::EtaPiGammaGammaDecayer::_dconst
private

The prefactor for the \(D(s,t,u)\) function.

Definition at line 268 of file EtaPiGammaGammaDecayer.h.

◆ _econst

vector<InvEnergy2> Herwig::EtaPiGammaGammaDecayer::_econst
private

The prefactor for the \(E(s,t,u)\) function.

Definition at line 273 of file EtaPiGammaGammaDecayer.h.

◆ _etamax

double Herwig::EtaPiGammaGammaDecayer::_etamax
private

the maximum weights for the \(\eta\) decay.

Definition at line 258 of file EtaPiGammaGammaDecayer.h.

◆ _etapmax

double Herwig::EtaPiGammaGammaDecayer::_etapmax
private

the maximum weights for the \(\eta'\) decay.

Definition at line 263 of file EtaPiGammaGammaDecayer.h.

◆ _fpi

Energy Herwig::EtaPiGammaGammaDecayer::_fpi
private

The pion decay constant, \(F_{\pi}\).

Definition at line 208 of file EtaPiGammaGammaDecayer.h.

◆ _grho

double Herwig::EtaPiGammaGammaDecayer::_grho
private

The coupling for the conversion of a rho to a photon, \(g\).

Definition at line 223 of file EtaPiGammaGammaDecayer.h.

◆ _grhoomega

InvEnergy Herwig::EtaPiGammaGammaDecayer::_grhoomega
private

The coupling \(g_{\omega\rho\pi}\) of the \(\rho\) to \(\omega\) and a \(\pi\).

Definition at line 203 of file EtaPiGammaGammaDecayer.h.

◆ _localparameters

bool Herwig::EtaPiGammaGammaDecayer::_localparameters
private

Use local values of the \(\rho\) mass and width.

Definition at line 238 of file EtaPiGammaGammaDecayer.h.

◆ _mpi

Energy Herwig::EtaPiGammaGammaDecayer::_mpi
private

The mass of the pion.

Definition at line 228 of file EtaPiGammaGammaDecayer.h.

◆ _ratiofpif0

double Herwig::EtaPiGammaGammaDecayer::_ratiofpif0
private

Ratios of the decay constants \(F_0/F_\pi\).

Definition at line 248 of file EtaPiGammaGammaDecayer.h.

◆ _ratiofpif8

double Herwig::EtaPiGammaGammaDecayer::_ratiofpif8
private

Ratios of the decay constants \(F_8/F_\pi\).

Definition at line 243 of file EtaPiGammaGammaDecayer.h.

◆ _rho

RhoDMatrix Herwig::EtaPiGammaGammaDecayer::_rho
mutableprivate

Spin density matrix.

Definition at line 278 of file EtaPiGammaGammaDecayer.h.

◆ _rhoconst

double Herwig::EtaPiGammaGammaDecayer::_rhoconst
private

Constant for the running \(\rho\) width calculation.

Definition at line 233 of file EtaPiGammaGammaDecayer.h.

◆ _rhomass

Energy Herwig::EtaPiGammaGammaDecayer::_rhomass
private

The mass of the \(\rho\).

Definition at line 213 of file EtaPiGammaGammaDecayer.h.

◆ _rhowidth

Energy Herwig::EtaPiGammaGammaDecayer::_rhowidth
private

The width of the \(\rho\).

Definition at line 218 of file EtaPiGammaGammaDecayer.h.

◆ _theta

double Herwig::EtaPiGammaGammaDecayer::_theta
private

the mixing angle, \(\theta\).

Definition at line 253 of file EtaPiGammaGammaDecayer.h.

◆ _vectors

vector<Helicity::LorentzPolarizationVector> Herwig::EtaPiGammaGammaDecayer::_vectors[2]
mutableprivate

Polarization vectors for the photons.

Definition at line 283 of file EtaPiGammaGammaDecayer.h.


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