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Herwig 7.3.0
Herwig::a1ThreePionDecayer Class Reference

The a1ThreePionDecayer class is designed to implement the decay of the a_1 to three pions. More...

#include <a1ThreePionDecayer.h>

Inheritance diagram for Herwig::a1ThreePionDecayer:

Public Member Functions

 a1ThreePionDecayer ()
 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.

vector< Energy > _rhomass
 Mass of the rho resonances.
 
vector< Energy > _rhowidth
 Width of the rho resonaces.
 
vector< Energy > _prho
 Momentum of the pions produced in the \(\rho\) decay.
 
vector< Energy2 > _hm2
 The function \(h(q^2)\) evaluated at \(q^2=M^2_{\rho_k}\).
 
vector< Energy2 > _rhoD
 The normalization factor for the \(\rho_k\) propagator factor.
 
vector< double > _dhdq2m2
 The \(\frac{dh}{dq^2}\) function in the rho propagator evaluated at \(q^2=m^2\) for the different \(\rho\) multiplets.
 
Energy _sigmamass
 The mass of the \(\sigma\) meson.
 
Energy _sigmawidth
 The width of the \(\sigma\) meson.
 
Energy _psigma
 The momenta of the pions produced in the \(\sigma\) meson decay.
 
Energy _mpi
 The mass of the pion, \(m_\pi\).
 
Energy2 _mpi2
 The mass of the pion, \(m^2_\pi\).
 
Energy2 _lambda2
 The \(\Lambda^2\) parameter for the \(a_1\) form factor.
 
Energy2 _a1mass2
 The mass squared of the \(a_1\) meson, \(m_{a_1}^2\).
 
Complex _zsigma
 The \(z\) coupling for the \(\sigma\) resonance.
 
double _zmag
 The magnitude of the \(z\) \(\sigma\) coupling.
 
double _zphase
 The phase of the \(z\) \(\sigma\) coupling.
 
vector< Complex_rhocoupling
 \(g_{\rho_k}\) is the coupling of the \(k\) th \(\rho\) multiplet.
 
vector< double > _rhomag
 Magnitude of the rho coupling.
 
vector< double > _rhophase
 Phase of the rho coupling.
 
double _coupling
 The overall coupling for the decay.
 
bool _localparameters
 use local values of the mass parameters
 
vector< double > _zerowgts
 Weights for the channels for the zero charged pion channel.
 
vector< double > _onewgts
 Weights for the channels for the one charged pion channel.
 
vector< double > _twowgts
 Weights for the channels for the two charged pion channel.
 
vector< double > _threewgts
 Weights for the channels for the three charged pion channel.
 
double _zeromax
 Maximum weight for the zero charged pion channel.
 
double _onemax
 Maximum weight for the one charged pion channel.
 
double _twomax
 Maximum weight for the two charged pion channel.
 
double _threemax
 Maximum weight for the three charged pion channel.
 
RhoDMatrix _rho
 Spin density matrix.
 
vector< Helicity::LorentzPolarizationVector_vectors
 Polarization vectors.
 
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.
 
a1ThreePionDecayeroperator= (const a1ThreePionDecayer &)=delete
 Private and non-existent assignment operator.
 
Complex sigmaBreitWigner (Energy2 q2) const
 Breit-wigner for the \(\sigma\), this is \(\frac1{D_\sigma(q^2)}\).
 
double a1FormFactor (Energy2 q2) const
 The \(a_1\) form factor, \(F_{a_1}(q^2)\).
 
Complex rhoBreitWigner (Energy2 q2, int ires) const
 Breit-Wigner for the \(\rho\), this is \(\frac1{D_{\rho_k}(q^2)}\).
 
Energy2 DParameter (int ires) const
 Normalisation factor for the \(\rho\) propagator to ensure \(D(0)=-1\).
 
double dhdq2Parameter (int ires) const
 The \(\frac{dh}{dq^2}\) function in the rho propagator evaluated at \(q^2=m^2\).
 
Energy2 hFunction (const Energy q) const
 The \(h(q^2)\) function in the \(\rho\) propagator.
 
Energy4 lambda (Energy2 a, Energy2 b, Energy2 c) const
 Momentum Function.
 

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 a1ThreePionDecayer class is designed to implement the decay of the a_1 to three pions.

The model used is one based on the Novosibirsk four pion current used in TAUOLA.

  • The matrix element for the decay \(a_1^0\to\pi^0\pi^0\pi^0\) is

\[J^\mu =\frac{F_{a_1}(q^2)g}{qM^2_{\rho_0}}\epsilon_\mu\left[ q^2z \sum_i p^\mu_i \frac1{D_\sigma(s_i)}\right]\]

  • The matrix element for the decay \(a_1^+\to\pi^0\pi^0\pi^+\) is

\[J^\mu =\frac{F_{a_1}(q^2)g}{qM^2_{\rho_0}}\epsilon_\mu\left[ q^2z\frac1{D_\sigma(s_3)} p_3^\mu +\sum_k g_{\rho_k}\left\{ \frac1{D_{\rho_k}(s_1)}\left(p_0\cdot p_3p_2^\mu-p_0\cdot p_2p_3^\mu\right) +\frac1{D_{\rho_k}(s_2)}\left(p_0\cdot p_3p_1^\mu-p_0\cdot p_1p_3^\mu\right) \right\} \right]\]

  • The matrix element for the decay \(a_10\to\pi^+\pi^-\pi^0\) is

\[J^\mu =\frac{F_{a_1}(q^2)g}{qM^2_{\rho_0}}\left[ q^2z\frac1{D_\sigma(s_3)}p_3^\mu +\sum_k g_{\rho_k}\left\{ \frac1{D_{\rho_k}(s_1)}\left(p_0\cdot p_3p_2^\mu-p_0\cdot p_2p_3^\mu\right) +\frac1{D_{\rho_k}(s_2)}\left(p_0\cdot p_3p_1^\mu-p_0\cdot p_1p_3^\mu\right)\right\} \right]\]

  • The current for the decay \(a_1^+\to\pi^+\pi^+\pi^-\) is

\[J^\mu = \frac{F_{a_1}(q^2)g}{qM^2_{\rho_0}}\left[ q^2z\left(\frac1{D_\sigma(s_1)}p_1^\mu+\frac1{D_\sigma(s_2)}p_2^\mu\right) -\sum_k g_{\rho_k}\left\{ \frac1{D_{\rho_k}(s_1)}\left(p_0\cdot p_3p_2^\mu-p_0\cdot p_2p_3^\mu\right) +\frac1{D_{\rho_k}(s_2)}\left(p_0\cdot p_3p_1^\mu-p_0\cdot p_1p_3^\mu\right)\right\} \right]\]

  • The denominator factor is

    \[D_\sigma(q^2) = q^2-M^2+iM\Gamma\frac{g_\sigma(q^2)}{g_\sigma(M^2)}\]

    where \(g(s) = \left(1-4\frac{m_{\pi}^2}{s}\right)\) for the \(\sigma\) meson, and

    \[D_{\rho_k}(q^2) = q^2-M^2_{\rho_k}-M_{\rho_k}\Gamma_{\rho_k}dm(q^2) +iM_{\rho_k}\Gamma_{\rho_k}\frac{g_{\rho_k}(q^2)}{g_{\rho_k}(M^2)} \]

    for the \(\rho\).

The propagator factors are normalized such that \(D(0)=-1\).

Here

\[dm(q^2) = \frac1{g_{\rho_k}(M^2_{\rho_k}}\left(h_{\rho_k}(q^2)-h_{\rho_k}(M^2_{\rho_k} -\left.(q^2-M^2_{\rho_k})\frac{dh_{\rho_k}(q^2)}{dq^2}\right|_{q^2=M^2_{\rho_k}} \right)\]

where

\[h_{\rho_k}(q^2) = \left\{ \begin{array}{cc} \frac{\sqrt{1-\frac{4m_\pi^2}{q^2}}\ln\left(\frac{1+\sqrt{1-\frac{4m_\pi^2}{q^2}}}{1-\sqrt{1-\frac{4m_\pi^2}{q^2}}}\right)(q^2-4m_\pi^2)}\pi & {\rm for\ } q^2>4m_\pi^2 \\ -8\frac{m_\pi^2}{\pi} & {\rm for\ } q^2=0\,{\rm GeV^2} \\ 0 & {\rm otherwise} \end{array}\right.\]

The \(a_1\) form factor for the off-shell \(a_1\) is given by

\[F_{a_1}(q^2) = \frac{\left(1+m^2_{a_1}/\Lambda^2\right)} {\left(1+ q^2/\Lambda^2\right)}.\]

The masses and couplings are

  • \(z\) is the relative coupling of the \(\sigma\).
  • \(m_\pi\) is the mass of the pion.
  • \(g_{\rho_k}\) is the coupling of the \(k\)th \(\rho\) multiplet.
  • \(M_{\rho_k}\) the mass of the \(k\)th \(\rho\) resonance.
  • \(\Gamma_{\rho_k}\) the width of the \(k\)th \(\rho\) resonance.
  • \(M_\sigma\) the mass of the \(\sigma\) meson.
  • \(\Gamma_\sigma\) the width of the \(\sigma\) meson.
  • \(m_{a_1}\) the mass of the \(a_1\) meson.
  • \(\Lambda^2\) the mass parameter for the \(a_1\) form factor.
    See also
    FourPionNovosibirskCurrent
    DecayIntegrator

Definition at line 102 of file a1ThreePionDecayer.h.

Member Function Documentation

◆ a1FormFactor()

double Herwig::a1ThreePionDecayer::a1FormFactor ( Energy2  q2) const
inlineprivate

The \(a_1\) form factor, \(F_{a_1}(q^2)\).

Parameters
q2The scale, \(q^2\).
Returns
The form factor.

Definition at line 258 of file a1ThreePionDecayer.h.

References _a1mass2, and _lambda2.

◆ clone()

virtual IBPtr Herwig::a1ThreePionDecayer::clone ( ) const
inlineprotectedvirtual

Make a simple clone of this object.

Returns
a pointer to the new object.

Implements ThePEG::InterfacedBase.

Definition at line 203 of file a1ThreePionDecayer.h.

◆ constructSpinInfo()

virtual void Herwig::a1ThreePionDecayer::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::a1ThreePionDecayer::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.

◆ dhdq2Parameter()

double Herwig::a1ThreePionDecayer::dhdq2Parameter ( int  ires) const
inlineprivate

The \(\frac{dh}{dq^2}\) function in the rho propagator evaluated at \(q^2=m^2\).

Parameters
iresThe \(\rho\) resonance for the function
Returns
\(\frac{dh}{dq^2}\) evaluated at \(q^2=m^2\).

Definition at line 305 of file a1ThreePionDecayer.h.

References _mpi2, _rhomass, ThePEG::Constants::pi, ThePEG::sqr(), and ThePEG::sqrt().

◆ doinit()

virtual void Herwig::a1ThreePionDecayer::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::a1ThreePionDecayer::doinitrun ( )
protectedvirtual

Initialize this object to the begining of the run phase.

Reimplemented from Herwig::DecayIntegrator.

◆ DParameter()

Energy2 Herwig::a1ThreePionDecayer::DParameter ( int  ires) const
inlineprivate

Normalisation factor for the \(\rho\) propagator to ensure \(D(0)=-1\).

Parameters
iresThe \(\rho\) multiplet.
Returns
The normalisation factor.

Definition at line 294 of file a1ThreePionDecayer.h.

References _dhdq2m2, _hm2, _prho, _rhomass, _rhowidth, hFunction(), ThePEG::sqr(), and ThePEG::ZERO.

◆ fullclone()

virtual IBPtr Herwig::a1ThreePionDecayer::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 209 of file a1ThreePionDecayer.h.

◆ hFunction()

Energy2 Herwig::a1ThreePionDecayer::hFunction ( const Energy  q) const
inlineprivate

The \(h(q^2)\) function in the \(\rho\) propagator.

Parameters
qThe scale, \(q\).
Returns
The function \(h(q^2)\).

Definition at line 317 of file a1ThreePionDecayer.h.

References _mpi2, ThePEG::Constants::pi, ThePEG::sqr(), ThePEG::sqrt(), and ThePEG::ZERO.

Referenced by DParameter(), and rhoBreitWigner().

◆ lambda()

Energy4 Herwig::a1ThreePionDecayer::lambda ( Energy2  a,
Energy2  b,
Energy2  c 
) const
inlineprivate

Momentum Function.

Definition at line 332 of file a1ThreePionDecayer.h.

References ThePEG::sqr().

◆ me2()

double Herwig::a1ThreePionDecayer::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::a1ThreePionDecayer::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::a1ThreePionDecayer::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::a1ThreePionDecayer::persistentOutput ( PersistentOStream os) const

Function used to write out object persistently.

Parameters
osthe persistent output stream written to.

◆ rhoBreitWigner()

Complex Herwig::a1ThreePionDecayer::rhoBreitWigner ( Energy2  q2,
int  ires 
) const
inlineprivate

Breit-Wigner for the \(\rho\), this is \(\frac1{D_{\rho_k}(q^2)}\).

Parameters
q2The scale, \(q^2\).
iresThe \(\rho\) multiplet.
Returns
The Breit-Wigner

Definition at line 268 of file a1ThreePionDecayer.h.

References _dhdq2m2, _hm2, _mpi, _mpi2, _prho, _rhoD, _rhomass, _rhowidth, hFunction(), Herwig::Kinematics::pstarTwoBodyDecay(), and ThePEG::sqrt().

◆ sigmaBreitWigner()

Complex Herwig::a1ThreePionDecayer::sigmaBreitWigner ( Energy2  q2) const
inlineprivate

Breit-wigner for the \(\sigma\), this is \(\frac1{D_\sigma(q^2)}\).

Parameters
q2The scale, \(q^2\).
Returns
The Breit-Wigner

Definition at line 243 of file a1ThreePionDecayer.h.

References _mpi, _psigma, _sigmamass, _sigmawidth, Herwig::Kinematics::pstarTwoBodyDecay(), and ThePEG::sqrt().

◆ threeBodyMatrixElement()

virtual double Herwig::a1ThreePionDecayer::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::a1ThreePionDecayer::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

◆ _a1mass2

Energy2 Herwig::a1ThreePionDecayer::_a1mass2
private

The mass squared of the \(a_1\) meson, \(m_{a_1}^2\).

Definition at line 402 of file a1ThreePionDecayer.h.

Referenced by a1FormFactor().

◆ _coupling

double Herwig::a1ThreePionDecayer::_coupling
private

The overall coupling for the decay.

Definition at line 437 of file a1ThreePionDecayer.h.

◆ _dhdq2m2

vector<double> Herwig::a1ThreePionDecayer::_dhdq2m2
private

The \(\frac{dh}{dq^2}\) function in the rho propagator evaluated at \(q^2=m^2\) for the different \(\rho\) multiplets.

Definition at line 367 of file a1ThreePionDecayer.h.

Referenced by DParameter(), and rhoBreitWigner().

◆ _hm2

vector<Energy2> Herwig::a1ThreePionDecayer::_hm2
private

The function \(h(q^2)\) evaluated at \(q^2=M^2_{\rho_k}\).

Definition at line 356 of file a1ThreePionDecayer.h.

Referenced by DParameter(), and rhoBreitWigner().

◆ _lambda2

Energy2 Herwig::a1ThreePionDecayer::_lambda2
private

The \(\Lambda^2\) parameter for the \(a_1\) form factor.

Definition at line 397 of file a1ThreePionDecayer.h.

Referenced by a1FormFactor().

◆ _localparameters

bool Herwig::a1ThreePionDecayer::_localparameters
private

use local values of the mass parameters

Definition at line 442 of file a1ThreePionDecayer.h.

◆ _mpi

Energy Herwig::a1ThreePionDecayer::_mpi
private

The mass of the pion, \(m_\pi\).

Definition at line 387 of file a1ThreePionDecayer.h.

Referenced by rhoBreitWigner(), and sigmaBreitWigner().

◆ _mpi2

Energy2 Herwig::a1ThreePionDecayer::_mpi2
private

The mass of the pion, \(m^2_\pi\).

Definition at line 392 of file a1ThreePionDecayer.h.

Referenced by dhdq2Parameter(), hFunction(), and rhoBreitWigner().

◆ _onemax

double Herwig::a1ThreePionDecayer::_onemax
mutableprivate

Maximum weight for the one charged pion channel.

Definition at line 472 of file a1ThreePionDecayer.h.

◆ _onewgts

vector<double> Herwig::a1ThreePionDecayer::_onewgts
mutableprivate

Weights for the channels for the one charged pion channel.

Definition at line 452 of file a1ThreePionDecayer.h.

◆ _prho

vector<Energy> Herwig::a1ThreePionDecayer::_prho
private

Momentum of the pions produced in the \(\rho\) decay.

Definition at line 351 of file a1ThreePionDecayer.h.

Referenced by DParameter(), and rhoBreitWigner().

◆ _psigma

Energy Herwig::a1ThreePionDecayer::_psigma
private

The momenta of the pions produced in the \(\sigma\) meson decay.

Definition at line 382 of file a1ThreePionDecayer.h.

Referenced by sigmaBreitWigner().

◆ _rho

RhoDMatrix Herwig::a1ThreePionDecayer::_rho
mutableprivate

Spin density matrix.

Definition at line 487 of file a1ThreePionDecayer.h.

◆ _rhocoupling

vector<Complex> Herwig::a1ThreePionDecayer::_rhocoupling
private

\(g_{\rho_k}\) is the coupling of the \(k\) th \(\rho\) multiplet.

Definition at line 422 of file a1ThreePionDecayer.h.

◆ _rhoD

vector<Energy2> Herwig::a1ThreePionDecayer::_rhoD
private

The normalization factor for the \(\rho_k\) propagator factor.

Definition at line 361 of file a1ThreePionDecayer.h.

Referenced by rhoBreitWigner().

◆ _rhomag

vector<double> Herwig::a1ThreePionDecayer::_rhomag
private

Magnitude of the rho coupling.

Definition at line 427 of file a1ThreePionDecayer.h.

◆ _rhomass

vector<Energy> Herwig::a1ThreePionDecayer::_rhomass
private

Mass of the rho resonances.

Definition at line 341 of file a1ThreePionDecayer.h.

Referenced by dhdq2Parameter(), DParameter(), and rhoBreitWigner().

◆ _rhophase

vector<double> Herwig::a1ThreePionDecayer::_rhophase
private

Phase of the rho coupling.

Definition at line 432 of file a1ThreePionDecayer.h.

◆ _rhowidth

vector<Energy> Herwig::a1ThreePionDecayer::_rhowidth
private

Width of the rho resonaces.

Definition at line 346 of file a1ThreePionDecayer.h.

Referenced by DParameter(), and rhoBreitWigner().

◆ _sigmamass

Energy Herwig::a1ThreePionDecayer::_sigmamass
private

The mass of the \(\sigma\) meson.

Definition at line 372 of file a1ThreePionDecayer.h.

Referenced by sigmaBreitWigner().

◆ _sigmawidth

Energy Herwig::a1ThreePionDecayer::_sigmawidth
private

The width of the \(\sigma\) meson.

Definition at line 377 of file a1ThreePionDecayer.h.

Referenced by sigmaBreitWigner().

◆ _threemax

double Herwig::a1ThreePionDecayer::_threemax
mutableprivate

Maximum weight for the three charged pion channel.

Definition at line 482 of file a1ThreePionDecayer.h.

◆ _threewgts

vector<double> Herwig::a1ThreePionDecayer::_threewgts
mutableprivate

Weights for the channels for the three charged pion channel.

Definition at line 462 of file a1ThreePionDecayer.h.

◆ _twomax

double Herwig::a1ThreePionDecayer::_twomax
mutableprivate

Maximum weight for the two charged pion channel.

Definition at line 477 of file a1ThreePionDecayer.h.

◆ _twowgts

vector<double> Herwig::a1ThreePionDecayer::_twowgts
mutableprivate

Weights for the channels for the two charged pion channel.

Definition at line 457 of file a1ThreePionDecayer.h.

◆ _vectors

vector<Helicity::LorentzPolarizationVector> Herwig::a1ThreePionDecayer::_vectors
mutableprivate

Polarization vectors.

Definition at line 492 of file a1ThreePionDecayer.h.

◆ _zeromax

double Herwig::a1ThreePionDecayer::_zeromax
mutableprivate

Maximum weight for the zero charged pion channel.

Definition at line 467 of file a1ThreePionDecayer.h.

◆ _zerowgts

vector<double> Herwig::a1ThreePionDecayer::_zerowgts
mutableprivate

Weights for the channels for the zero charged pion channel.

Definition at line 447 of file a1ThreePionDecayer.h.

◆ _zmag

double Herwig::a1ThreePionDecayer::_zmag
private

The magnitude of the \(z\) \(\sigma\) coupling.

Definition at line 412 of file a1ThreePionDecayer.h.

◆ _zphase

double Herwig::a1ThreePionDecayer::_zphase
private

The phase of the \(z\) \(\sigma\) coupling.

Definition at line 417 of file a1ThreePionDecayer.h.

◆ _zsigma

Complex Herwig::a1ThreePionDecayer::_zsigma
private

The \(z\) coupling for the \(\sigma\) resonance.

Definition at line 407 of file a1ThreePionDecayer.h.


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