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Herwig  7.2.1
Herwig::VectorMeson2FermionDecayer Class Reference

The VectorMeson2FermionDecayer class is designed for the decay of a vector meson to a fermion-antifermion pair. More...

#include <VectorMeson2FermionDecayer.h>

Inheritance diagram for Herwig::VectorMeson2FermionDecayer:

Public Member Functions

 VectorMeson2FermionDecayer ()
 Default constructor.
 
virtual int modeNumber (bool &cc, tcPDPtr parent, const tPDVector &children) const
 Which of the possible decays is required. More...
 
double me2 (const int ichan, const Particle &part, const ParticleVector &decay, MEOption meopt) const
 Return the matrix element squared for a given mode and phase-space channel. More...
 
bool twoBodyMEcode (const DecayMode &dm, int &mecode, double &coupling) const
 Specify the $1\to2$ matrix element to be used in the running width calculation. More...
 
virtual void dataBaseOutput (ofstream &os, bool header) const
 Output the setup information for the particle database. More...
 
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...
 
- Public Member Functions inherited from Herwig::DecayIntegrator
 DecayIntegrator ()
 Default constructor.
 
virtual bool accept (tcPDPtr parent, const tPDVector &children) const
 Check if this decayer can perfom the decay for a particular mode. More...
 
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. More...
 
int imode () const
 The mode being used for this decay.
 
void addMode (DecayPhaseSpaceModePtr mode, double maxwgt, const vector< double > wgts) const
 Add a phase-space mode to the list. More...
 
DecayMEPtr ME () const
 The helicity amplitude matrix element for spin correlations.
 
virtual WidthCalculatorBasePtr threeBodyMEIntegrator (const DecayMode &dm) const
 Method to return an object to calculate the 3 (or higher body) partial width. More...
 
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. More...
 
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. More...
 
void setPartialWidth (const DecayMode &dm, int imode)
 Set the code for the partial width. More...
 
int findMode (const DecayMode &dm)
 Finds the phase-space mode corresponding to a given decay mode. More...
 
Energy epsilonPS () const
 Access to the epsilon parameter.
 
ParticleVector generatePhotons (const Particle &p, ParticleVector children)
 Members for the generation of QED radiation in the decays. More...
 
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. More...
 
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. More...
 
bool hasRealEmissionME ()
 Whether or not the real emission matrix element is implemented.
 
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...
 
- 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. More...
 
virtual ParticleVector decay (const DecayMode &dm, const Particle &p) const
 Perform a decay for a given DecayMode and a given Particle instance. More...
 
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...
 
bool initialize () const
 Access to the initialize variable.
 
bool databaseOutput () const
 Access the database output variable.
 
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. More...
 
virtual RealEmissionProcessPtr generateHardest (RealEmissionProcessPtr)
 Apply the POWHEG style correction.
 
- Public Member Functions inherited from ThePEG::Decayer
Ptr< Amplitude >::pointer amplitude () const
 
virtual bool needsFullStep () const
 
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
 
void persistentOutput (PersistentOStream &os) const
 
void persistentInput (PersistentIStream &is, int version)
 
virtual bool needsFullStep () const
 
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
 
void persistentOutput (PersistentOStream &os) const
 
void persistentInput (PersistentIStream &is, int version)
 
- Public Member Functions inherited from 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
 
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 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())
 
 Named (const Named &)=default
 
const string & name () const
 
bool operator== (const Named &other) const
 
bool operator< (const Named &other) const
 

Static Public Member Functions

static void Init ()
 Standard Init function used to initialize the interfaces.
 
- Static Public Member Functions inherited from Herwig::DecayIntegrator
static void Init ()
 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. More...
 
- Static Public Member Functions inherited from ThePEG::Decayer
static ParticleVector DecayParticle (tPPtr parent, Step &step, long maxtry=1000)
 
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 ()
 

Protected Member Functions

Clone Methods.
virtual IBPtr clone () const
 Make a simple clone of this object. More...
 
virtual IBPtr fullclone () const
 Make a clone of this object, possibly modifying the cloned object to make it sane. More...
 
Standard Interfaced functions.
virtual void doinit ()
 Initialize this object after the setup phase before saving and EventGenerator to disk. More...
 
virtual void doinitrun ()
 Initialize this object to the begining of the run phase.
 
- 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. More...
 
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.
 
void resetIntermediate (tcPDPtr part, Energy mass, Energy width)
 Reset the properities of all intermediates. More...
 
unsigned int numberModes () const
 Number of decay modes.
 
tDecayPhaseSpaceModePtr mode (unsigned int)
 Pointer to a mode.
 
tcDecayPhaseSpaceModePtr mode (unsigned int) const
 Pointer to a mode.
 
bool generateIntermediates () const
 Get whether or not the intermediates are included.
 
void generateIntermediates (bool in)
 Set whether or not the intermediates are included.
 
Energy initializePhaseSpaceMode (unsigned int imode, bool init, bool onShell=false) const
 Initialize the phase-space mode. More...
 
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.
 
- Protected Member Functions inherited from Herwig::HwDecayerBase
void fixRho (RhoDMatrix &) const
 Set rho to be diagonal if no correlations.
 
virtual void dofinish ()
 Finalize this object. More...
 
- 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
 InterfacedBase (string newName)
 
 InterfacedBase (const InterfacedBase &i)
 
virtual void readSetup (istream &is)
 
virtual void doupdate ()
 
virtual IVector getReferences ()
 
virtual void rebind (const TranslationMap &)
 
virtual void readSetup (istream &is)
 
virtual void doupdate ()
 
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

VectorMeson2FermionDecayeroperator= (const VectorMeson2FermionDecayer &)=delete
 Private and non-existent assignment operator.
 

Private Attributes

vector< double > _coupling
 coupling for a decay
 
vector< int > _incoming
 the PDG codes for the incoming particles
 
vector< int > _outgoingf
 the PDG codes for the outgoing fermion
 
vector< int > _outgoinga
 the PDG codes for the outgoing antifermion.
 
vector< double > _maxweight
 maximum weight for a decay
 
unsigned int _initsize
 Initial size of the vectors.
 
RhoDMatrix _rho
 Spin density matrix.
 
vector< Helicity::LorentzPolarizationVector_vectors
 Polarization vectors for the decaying particle.
 
vector< Helicity::LorentzSpinor< SqrtEnergy > > _wave
 Spinors for the decay products.
 
vector< Helicity::LorentzSpinorBar< SqrtEnergy > > _wavebar
 barred spinors for the decay products
 

Additional Inherited Members

- Public Types inherited from Herwig::DecayIntegrator
enum  MEOption { Initialize, Calculate, Terminate }
 Enum for the matrix element option.
 
- 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
 
- 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 VectorMeson2FermionDecayer class is designed for the decay of a vector meson to a fermion-antifermion pair.

This class is mainly used for the decay of the vector mesons to electron and muon pairs but can also be used for the decay of charmonium, e.g. $J/\psi$, or bottomonium decays to baryons, e.g. $p\bar{p}$ and $n\bar{n}$.

In this case the matrix element is taken to have the form

\[\mathcal{M} = g\epsilon_\mu \bar{u}(p_f)\gamma^\mu u(p_{\bar{f}}).\]

The incoming vector mesons together with their decay products and the coupling $g$ can be specified using the interfaces for the class. The maximum weights for the decays can be calculated using the Initialize interface of the DecayIntegrator class or specified using the interface.

The incoming and outgoing particles, couplings and maximum weights for many of the common $V\to f\bar{f}$ decays are specified in the default constructor.

See also
DecayIntegrator
The interfaces defined for VectorMeson2FermionDecayer.

Definition at line 46 of file VectorMeson2FermionDecayer.h.

Member Function Documentation

◆ clone()

virtual IBPtr Herwig::VectorMeson2FermionDecayer::clone ( ) const
inlineprotectedvirtual

Make a simple clone of this object.

Returns
a pointer to the new object.

Implements ThePEG::InterfacedBase.

Definition at line 123 of file VectorMeson2FermionDecayer.h.

◆ dataBaseOutput()

virtual void Herwig::VectorMeson2FermionDecayer::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::VectorMeson2FermionDecayer::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.

◆ fullclone()

virtual IBPtr Herwig::VectorMeson2FermionDecayer::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 129 of file VectorMeson2FermionDecayer.h.

◆ me2()

double Herwig::VectorMeson2FermionDecayer::me2 ( const int  ichan,
const Particle part,
const ParticleVector decay,
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.
decayThe 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::VectorMeson2FermionDecayer::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::VectorMeson2FermionDecayer::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::VectorMeson2FermionDecayer::persistentOutput ( PersistentOStream os) const

Function used to write out object persistently.

Parameters
osthe persistent output stream written to.

◆ twoBodyMEcode()

bool Herwig::VectorMeson2FermionDecayer::twoBodyMEcode ( const DecayMode dm,
int &  mecode,
double &  coupling 
) const
virtual

Specify the $1\to2$ matrix element to be used in the running width calculation.

Parameters
dmThe DecayMode
mecodeThe code for the matrix element as described in the GenericWidthGenerator class, in this case 2.
couplingThe coupling for the matrix element.
Returns
True or False if this mode can be handled.

Reimplemented from Herwig::DecayIntegrator.


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