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Herwig 7.3.0
Herwig::TauDecayer Class Reference

The TauDecayer class performs the decay of the \(\tau\). More...

#include <TauDecayer.h>

Inheritance diagram for Herwig::TauDecayer:

Public Member Functions

 TauDecayer ()
 Default constructor.
 
virtual bool accept (tcPDPtr parent, const tPDVector &children) const
 Check if this decayer can perfom the decay for a particular mode.
 
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.
 
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.

vector< unsigned int > modeMap_
 mapping of the modes to the currents
 
WeakCurrentPtr current_
 the hadronic current
 
vector< int > wgtLoc_
 location of the weights
 
vector< double > wgtMax_
 the maximum weight
 
vector< double > weights_
 The weights for the different channels.
 
vector< LorentzSpinor< SqrtEnergy > > inSpin_
 The spinors for the decaying particle.
 
vector< LorentzSpinorBar< SqrtEnergy > > inBar_
 Barred spinors for the deaying particle.
 
RhoDMatrix rho_
 Rho matrix.
 
vector< unsigned int > constants_
 Maps for the vectors.
 
vector< PDT::SpiniSpin_
 Spins of the particles.
 
bool polOpt_
 Option to force the polarizations of the tau leptons.
 
double tauMpol_
 Polarization for \(\tau^-\).
 
double tauPpol_
 Polarization of \(\tau^+\).
 
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.
 
TauDecayeroperator= (const TauDecayer &)=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 TauDecayer class performs the decay of the \(\tau\).

The matrix element for \(\tau\) decay can be split into a leptonic current describing the weak decay of the decay to a neutrino and a highly virtual \(W\) combined with a hadronic current for the virtual \(W\) decay.

The matrix element has the form

\[\mathcal{M} = \frac{G_F}{\sqrt{2}}\bar{u}(p_{\nu_\tau}) \gamma^\mu\left(1-\gamma^5\right)u(p_{\tau}) J_\mu,\]

where

  • \(G_F\) is the Fermi constant,
  • \(p_{\nu_\tau}\) is the momentum of the \(\tau\) neutrino,
  • \(p_{\tau}\) is the momentum of the \(\tau\),
  • \( J_\mu\) is the hadronic current.

    The leptonic part of this matrix element is implemented in this class together with a WeakCurrent member which calculates the hadronic current \( J_\mu\). This allows a range of \(\tau\) decays to be constructed via the repository using the interfaces.

See also
DecayIntegrator.
WeakCurrent

Definition at line 50 of file TauDecayer.h.

Constructor & Destructor Documentation

◆ TauDecayer()

Herwig::TauDecayer::TauDecayer ( )
inline

Default constructor.

Definition at line 57 of file TauDecayer.h.

References Herwig::DecayIntegrator::generateIntermediates().

Member Function Documentation

◆ accept()

virtual bool Herwig::TauDecayer::accept ( tcPDPtr  parent,
const tPDVector children 
) const
virtual

Check if this decayer can perfom the decay for a particular mode.

Parameters
parentThe decaying particle
childrenThe decay products

Reimplemented from Herwig::DecayIntegrator.

◆ clone()

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

Make a simple clone of this object.

Returns
a pointer to the new object.

Implements ThePEG::InterfacedBase.

Definition at line 133 of file TauDecayer.h.

◆ constructSpinInfo()

virtual void Herwig::TauDecayer::constructSpinInfo ( const Particle part,
ParticleVector  outgoing 
) const
virtual

Construct the SpinInfos for the particles produced in the decay.

Implements Herwig::DecayIntegrator.

◆ dataBaseOutput()

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

Output the setup information for the particle database.

Reimplemented from Herwig::DecayIntegrator.

◆ doinit()

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

Initialize this object to the begining of the run phase.

Reimplemented from Herwig::DecayIntegrator.

◆ fullclone()

virtual IBPtr Herwig::TauDecayer::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 139 of file TauDecayer.h.

◆ me2()

double Herwig::TauDecayer::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::TauDecayer::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::TauDecayer::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::TauDecayer::persistentOutput ( PersistentOStream os) const

Function used to write out object persistently.

Parameters
osthe persistent output stream written to.

Member Data Documentation

◆ constants_

vector<unsigned int> Herwig::TauDecayer::constants_
mutableprivate

Maps for the vectors.

Definition at line 212 of file TauDecayer.h.

◆ current_

WeakCurrentPtr Herwig::TauDecayer::current_
private

the hadronic current

Definition at line 177 of file TauDecayer.h.

◆ inBar_

vector<LorentzSpinorBar<SqrtEnergy> > Herwig::TauDecayer::inBar_
mutableprivate

Barred spinors for the deaying particle.

Definition at line 202 of file TauDecayer.h.

◆ inSpin_

vector<LorentzSpinor <SqrtEnergy> > Herwig::TauDecayer::inSpin_
mutableprivate

The spinors for the decaying particle.

Definition at line 197 of file TauDecayer.h.

◆ iSpin_

vector<PDT::Spin> Herwig::TauDecayer::iSpin_
mutableprivate

Spins of the particles.

Definition at line 217 of file TauDecayer.h.

◆ modeMap_

vector<unsigned int> Herwig::TauDecayer::modeMap_
private

mapping of the modes to the currents

Definition at line 172 of file TauDecayer.h.

◆ polOpt_

bool Herwig::TauDecayer::polOpt_
private

Option to force the polarizations of the tau leptons.

Definition at line 222 of file TauDecayer.h.

◆ rho_

RhoDMatrix Herwig::TauDecayer::rho_
mutableprivate

Rho matrix.

Definition at line 207 of file TauDecayer.h.

◆ tauMpol_

double Herwig::TauDecayer::tauMpol_
private

Polarization for \(\tau^-\).

Definition at line 227 of file TauDecayer.h.

◆ tauPpol_

double Herwig::TauDecayer::tauPpol_
private

Polarization of \(\tau^+\).

Definition at line 232 of file TauDecayer.h.

◆ weights_

vector<double> Herwig::TauDecayer::weights_
private

The weights for the different channels.

Definition at line 192 of file TauDecayer.h.

◆ wgtLoc_

vector<int> Herwig::TauDecayer::wgtLoc_
private

location of the weights

Definition at line 182 of file TauDecayer.h.

◆ wgtMax_

vector<double> Herwig::TauDecayer::wgtMax_
private

the maximum weight

Definition at line 187 of file TauDecayer.h.


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