Weak current for the production of two mesons via the $\rho$ or $K^*$ resonances. More...

#include <TwoMesonRhoKStarCurrent.h>

Inheritance diagram for Herwig::TwoMesonRhoKStarCurrent:

Public Member Functions
	TwoMesonRhoKStarCurrent ()
	Default constructor.
virtual vector < LorentzPolarizationVectorE >	current (const int imode, const int ichan, Energy &scale, const ParticleVector &decay, DecayIntegrator::MEOption meopt) const
	Hadronic current.
virtual bool	accept (vector< int > id)
	Accept the decay.
virtual unsigned int	decayMode (vector< int > id)
	Return the decay mode number for a given set of particles in the current.
virtual void	dataBaseOutput (ofstream &os, bool header, bool create) const
	Output the setup information for the particle database.
Methods for the construction of the phase space integrator.
virtual bool	createMode (int icharge, unsigned int imode, DecayPhaseSpaceModePtr mode, unsigned int iloc, unsigned int ires, DecayPhaseSpaceChannelPtr phase, Energy upp)
	Complete the construction of the decay mode for integration.
virtual tPDVector	particles (int icharge, unsigned int imode, int iq, int ia)
	The particles produced by the current.
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 Public Member Functions
static void	Init ()
	Standard Init function used to initialize the interfaces.
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.
Standard Interfaced functions.
virtual void	doinit ()
	Initialize this object after the setup phase before saving and EventGenerator to disk.
Private Member Functions
TwoMesonRhoKStarCurrent &	operator= (const TwoMesonRhoKStarCurrent &)
	Private and non-existent assignment operator.
Breit-Wigner functions
Complex	BreitWigner (Energy2 q2, unsigned int imodel, unsigned int itype, unsigned int ires) const
	-wave breit wigner for form-factors
double	GSModelDParameter (const unsigned int ires) const
	The parameter in the GS model of the propagator.
InvEnergy2	GSModeldhdq2Parameter (const unsigned int ires) const
	The $\frac{dh}{dq^2}$ function in the GS model for the propagator evaluated at .
double	GSModelhFunction (const unsigned int ires, const Energy q) const
	The function in the GS model.
Energy	pcm (const unsigned int ires, const Energy q) const
	The momentum of the decay products for the running width.
Private Attributes
int	_pimodel
	Model to use for the $\rho$ propagator.
int	_kmodel
	Model to use for the propagator.
bool	_rhoparameters
	Option not to use the physical masses and widths for the $\rho$ .
vector< Energy >	_rhomasses
	The masses of the $\rho$ resonances.
vector< Energy >	_rhowidths
	The widths of the $\rho$ resonances.
bool	_kstarparameters
	Option not to use the physical masses and widths for the .
vector< Energy >	_kstarmasses
	The masses of the resonances.
vector< Energy >	_kstarwidths
	The masses of the resonances.

vector< Complex >	_piwgt
	Weights for the different $\rho$ resonances in the current, $\alpha_k$ .
vector< double >	_pimag
	The magnitude for input.
vector< double >	_piphase
	The phase for input.

vector< Complex >	_kwgt
	Weights for the different resonances in the current, $\alpha_k$ .
vector< double >	_kmag
	The magnitude for input.
vector< double >	_kphase
	The phase for input.

vector< Energy >	_mass
	Parameters for the Breit-Wigners.
vector< Energy >	_width
	The widths of the resonances.
vector< Energy2 >	_mass2
	squares of the masses
vector< Energy2 >	_massw
	product of the mass and the width
vector< Energy >	_massa
	Masses of the decay products for the momentum calculation.
vector< Energy >	_massb
vector< Energy >	_mom
	The decay for the on-shell mass momentum.
vector< InvEnergy2 >	_dhdq2
	The function $\frac{dh}{dq^2}$ at for the GS form of the Breit-Wigner.
vector< double >	_hm2
	The function at for the GS form of the Breit-Wigner.
vector< double >	_dparam
	The parameter for the GS form of the Breit-Wigner.
Static Private Attributes
static ClassDescription < TwoMesonRhoKStarCurrent >	initTwoMesonRhoKStarCurrent
	Describe a concrete class with persistent data.

Detailed Description

Weak current for the production of two mesons via the $\rho$ or $K^*$ resonances.

These currents are taken from tau decays.

The current takes the form

$J^\mu = \frac{\sqrt{2}}{\sum_k\alpha_k}\left((p_1-p_2)^\mu-\frac{(p_1-p_2)\cdot q}{q^2}q^\mu))\right) \sum_k \alpha_k B_{R_k}(q^2)$

where

$p_{1,2}$ are the momenta of the outgoing mesons,
,
$B_{R_k}(q^2)$ is the Breit-Wigner distribution for the intermediate vector meson .
$\alpha_k$ is the weight for the resonance.

The Breit-Wigner term is summed over the $\rho$ or $K^*$ resonances that can contribute to a given decay.

The models of either Kuhn and Santamaria (Z. Phys. C48, 445 (1990)) or Gounaris and Sakurai Phys. Rev. Lett. 21, 244 (1968) are supported for the shape of the Breit-Wigner distribution. The mixing parameters are taken from Phys.Rev.D61:112002,2000 (CLEO) for the decay $\pi^\pm\pi^0$ and the CLEO version of TAUOLA for the $K\pi$ decays.

See also:: WeakDecayCurrent.

Author:: Peter Richardson

Definition at line 53 of file TwoMesonRhoKStarCurrent.h.

Member Function Documentation

virtual bool Herwig::TwoMesonRhoKStarCurrent::accept ( vector< int > id ) [virtual]

Accept the decay.

Checks the particles are the allowed mode.

Parameters:

id	The id's of the particles in the current.

Returns:: Can this current have the external particles specified.

Implements Herwig::WeakDecayCurrent.

Complex Herwig::TwoMesonRhoKStarCurrent::BreitWigner	(	Energy2	q2,
		unsigned int	imodel,
		unsigned int	itype,
		unsigned int	ires
	)		const `[inline, private]`

$p$ -wave breit wigner for form-factors

Parameters:

q2	The scale for the Breit-Wigner
imodel	Which of the two models for the Breit-Wigner shape to use.
itype	Whether this is a $\rho$ or resonance.
ires	Which of the different multiplets to use.

Returns:: The value of the Breit-Wigner distribution.

Definition at line 207 of file TwoMesonRhoKStarCurrent.h.

References sqr(), and sqrt().

virtual IBPtr Herwig::TwoMesonRhoKStarCurrent::clone ( ) const [inline, protected, virtual]

Make a simple clone of this object.

Returns:: a pointer to the new object.

Implements ThePEG::InterfacedBase.

Definition at line 161 of file TwoMesonRhoKStarCurrent.h.

virtual bool Herwig::TwoMesonRhoKStarCurrent::createMode	(	int	icharge,
		unsigned int	imode,
		DecayPhaseSpaceModePtr	mode,
		unsigned int	iloc,
		unsigned int	ires,
		DecayPhaseSpaceChannelPtr	phase,
		Energy	upp
	)		`[virtual]`

Complete the construction of the decay mode for integration.

This version just adds the intermediate resonances, two outgoing mesons and photon.

Parameters:

icharge	The total charge of the outgoing particles in the current.
imode	The mode in the current being asked for.
mode	The phase space mode for the integration
iloc	The location of the of the first particle from the current in the list of outgoing particles.
ires	The location of the first intermediate for the current.
phase	The prototype phase space channel for the integration.
upp	The maximum possible mass the particles in the current are allowed to have.

Returns:: Whether the current was sucessfully constructed.

Implements Herwig::WeakDecayCurrent.

virtual vector<LorentzPolarizationVectorE> Herwig::TwoMesonRhoKStarCurrent::current	(	const int	imode,
		const int	ichan,
		Energy &	scale,
		const ParticleVector &	decay,
		DecayIntegrator::MEOption	meopt
	)		const `[virtual]`

Hadronic current.

This version returns the hadronic current described above.

Parameters:

imode	The mode
ichan	The phase-space channel the current is needed for
scale	The invariant mass of the particles in the current.
decay	The decay products
meopt	Option for the calculation of the matrix element

Returns:: The current.

Implements Herwig::WeakDecayCurrent.

virtual void Herwig::TwoMesonRhoKStarCurrent::dataBaseOutput	(	ofstream &	os,
		bool	header,
		bool	create
	)		const `[virtual]`

Output the setup information for the particle database.

Parameters:

os	The stream to output the information to
header	Whether or not to output the information for MySQL
create	Whether or not to add a statement creating the object

Reimplemented from Herwig::WeakDecayCurrent.

virtual unsigned int Herwig::TwoMesonRhoKStarCurrent::decayMode ( vector< int > id ) [virtual]

Return the decay mode number for a given set of particles in the current.

Parameters:

id	The id's of the particles in the current.

Returns:: The number of the mode

Implements Herwig::WeakDecayCurrent.

virtual void Herwig::TwoMesonRhoKStarCurrent::doinit ( ) [protected, virtual]

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

Exceptions:

InitException if object could not be initialized properly.

Reimplemented from ThePEG::InterfacedBase.

virtual IBPtr Herwig::TwoMesonRhoKStarCurrent::fullclone ( ) const [inline, protected, virtual]

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 167 of file TwoMesonRhoKStarCurrent.h.

InvEnergy2 Herwig::TwoMesonRhoKStarCurrent::GSModeldhdq2Parameter ( const unsigned int ires ) const [inline, private]

The $\frac{dh}{dq^2}$ function in the GS model for the propagator evaluated at $q^2=m^2$ .

Parameters:

ires	Which of the $\rho$ or resonances to use

Returns:: The value of $\frac{dh}{dq^2}$ at .

Definition at line 254 of file TwoMesonRhoKStarCurrent.h.

References sqr().

double Herwig::TwoMesonRhoKStarCurrent::GSModelDParameter ( const unsigned int ires ) const [inline, private]

The $d$ parameter in the GS model of the propagator.

Parameters:

ires	Which of the $\rho$ or resonances to use

Returns:: The parameter

Definition at line 241 of file TwoMesonRhoKStarCurrent.h.

References ThePEG::Constants::pi, and sqr().

double Herwig::TwoMesonRhoKStarCurrent::GSModelhFunction	(	const unsigned int	ires,
		const Energy	q
	)		const `[inline, private]`

The $h$ function in the GS model.

Parameters:

ires	Which of the $\rho$ or resonances to use
q	The scale .

Returns:: The value of the function at scale .

Definition at line 267 of file TwoMesonRhoKStarCurrent.h.

virtual tPDVector Herwig::TwoMesonRhoKStarCurrent::particles	(	int	icharge,
		unsigned int	imode,
		int	iq,
		int	ia
	)		`[virtual]`

The particles produced by the current.

This just returns the two pseudoscalar mesons and the photon.

Parameters:

icharge	The total charge of the particles in the current.
imode	The mode for which the particles are being requested
iq	The PDG code for the quark
ia	The PDG code for the antiquark

Returns:: The external particles for the current.

Implements Herwig::WeakDecayCurrent.

Energy Herwig::TwoMesonRhoKStarCurrent::pcm	(	const unsigned int	ires,
		const Energy	q
	)		const `[inline, private]`

The momentum of the decay products for the running width.

Parameters:

ires	Which of the $\rho$ or resonances to use
q	The scale .

Returns:: The momenta of the decay products in the rest frame of the intermediate resonance.

Definition at line 280 of file TwoMesonRhoKStarCurrent.h.

References sqr(), sqrt(), and ZERO.

void Herwig::TwoMesonRhoKStarCurrent::persistentInput	(	PersistentIStream &	is,
		int	version
	)

Function used to read in object persistently.

Parameters:

is	the persistent input stream read from.
version	the version number of the object when written.

Reimplemented from Herwig::WeakDecayCurrent.

void Herwig::TwoMesonRhoKStarCurrent::persistentOutput ( PersistentOStream & os ) const

Function used to write out object persistently.

Parameters:

os	the persistent output stream written to.

Reimplemented from Herwig::WeakDecayCurrent.

Member Data Documentation

vector<Complex> Herwig::TwoMesonRhoKStarCurrent::_kwgt [private]

Weights for the different $K^*$ resonances in the current, $\alpha_k$ .

The Complex weight used in the calculation

Definition at line 317 of file TwoMesonRhoKStarCurrent.h.

vector<Energy> Herwig::TwoMesonRhoKStarCurrent::_mass [private]

Parameters for the Breit-Wigners.

The masses of the resonances

Definition at line 377 of file TwoMesonRhoKStarCurrent.h.

vector<Complex> Herwig::TwoMesonRhoKStarCurrent::_piwgt [private]

Weights for the different $\rho$ resonances in the current, $\alpha_k$ .

The Complex weight used in the calculation

Definition at line 297 of file TwoMesonRhoKStarCurrent.h.

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

TwoMesonRhoKStarCurrent.h

Public Member Functions

Static Public Member Functions

Protected Member Functions

Private Member Functions

Private Attributes

Static Private Attributes

Detailed Description

Member Function Documentation

Member Data Documentation