ThePEG::ClusterCollapser Class Reference

ClusterCollapser is a general StepHandler which can be called anywhere in the event generation (typically as a pre-handler to the hadronization or a post-hadnler to the cascade) to find colour-less clusters of partons which are deemed to have to small invariant mass to be hadronized in the normal way. More...

#include <ClusterCollapser.h>

Inheritance diagram for ThePEG::ClusterCollapser:

List of all members.

Public Types

typedef Ptr< FlavourGenerator >
::pointer FlavGenPtr

Declare a pointer to a FlavourGenerator object.

typedef multimap< Energy,
ColourSinglet > SingletMap

Declare a multimap of singlets indexed by their mass.

Public Member Functions

virtual vector< ColourSinglet > collapse (tPVector tagged, tStepPtr newstep)

Perform all necessary collapses.

virtual SingletMap getSinglets (const tPVector &tagged) const

Go through the tagged partons and extract all colour singlet combination of partons.

virtual ColourSinglet splitDiQuarkJunction (ColourSinglet &cs, tStepPtr newStep) const

If a singlet contains at least one diquark and a junction, split the diquark and split off a new colour singlet.

virtual ColourSinglet splitDiDiQuark (ColourSinglet &cs, tStepPtr newStep) const

If a singlet contains a simple string with diquarks in both ends, split them into quarks and split off a new colour singlet.

Energy cut () const

If the invariant mass of a cluster, minus the constituent masses of its partons is below this cut, it will be collapsed into one or two particles.

int nTry2 () const

The number of attempts to collapse a cluster into two particles, before it is collapsed into one particle.

virtual tcPDPtr pickFlavour () const

Pick a random flavour.

Standard constructors and destructors.

ClusterCollapser ()

The default constructor.

virtual ~ClusterCollapser ()

The destructor.

Virtual functions required by the StepHandler class.

virtual void handle (EventHandler &eh, const tPVector &tagged, const Hint &hint)

The main function called by the EventHandler class to perform a step.

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 bool diQuarkJunction (const ColourSinglet &cs)

Returns true iff the given singlet contains a junction and at least one diquark.

static bool diDiQuark (const ColourSinglet &cs)

Returns true iff the given singlet contains one string piece with diquarks in both ends.

static Energy mass (const ColourSinglet &cl)

Return the invariant mass of a cluster minus the constituent masses of its partons.

static void insert (SingletMap &mmap, const ColourSinglet &cl)

Insert a ColourSinglet object in a SingletMap.

static void Init ()

Standard Init function used to initialize the interfaces.

Protected Member Functions

virtual void collapse (tStepPtr newStep, const ColourSinglet &cs, const tPVector &tagged) const

Perform the actual collapse of a cluster into one hadron.

virtual bool collapse2 (tStepPtr newStep, const ColourSinglet &cs) const

Perform the actual collapse of a cluster into two hadrons.

virtual tPVector getCompensators (Energy mh, const ColourSinglet &cs, const tPVector &tagged, tStepPtr newStep) const

Get particles for compensation.

virtual tcPDPtr getHadron (const ColourSinglet &cs) const

Return a hadron into which the given cluster may collapse.

virtual tcPDPair getHadrons (const ColourSinglet &cs) const

Return a pair of hadrons into which the given cluster may collapse.

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 Attributes

Exception::Severity errorlevel

How should we respond to errors? 0 means do nothing, ie.

double pStrange

The relative probability to produce a s-sbar pair in a split as compared to a u-ubar or d-dbar pair.

Private Member Functions

ClusterCollapser & operator= (const ClusterCollapser &)

Private and non-existent assignment operator.

Private Attributes

Energy theEnergyCut

Energy cut.

int theNTry2

The number of attempts to collapse a cluster into two particles, before it is collapsed into one particle.

FlavGenPtr flavGen

The flavour generator object to use to combine quarks and diqurks into hadrons.

Static Private Attributes

static ClassDescription
< ClusterCollapser > initClusterCollapser

Describe a concrete class with persistent data.

Detailed Description

ClusterCollapser is a general StepHandler which can be called anywhere in the event generation (typically as a pre-handler to the hadronization or a post-hadnler to the cascade) to find colour-less clusters of partons which are deemed to have to small invariant mass to be hadronized in the normal way.

Instead these clusters are allowed to collapse into hadrons. Possible energy imbalance du to the clustering is compensated by shifting the momenta of nearby particles.

See also:: The interfaces defined for ClusterCollapser.

Definition at line 35 of file ClusterCollapser.h.

Member Typedef Documentation

typedef Ptr<FlavourGenerator>::pointer ThePEG::ClusterCollapser::FlavGenPtr

Declare a pointer to a FlavourGenerator object.

Definition at line 40 of file ClusterCollapser.h.

typedef multimap<Energy,ColourSinglet> ThePEG::ClusterCollapser::SingletMap

Declare a multimap of singlets indexed by their mass.

Definition at line 43 of file ClusterCollapser.h.

Member Function Documentation

virtual void ThePEG::ClusterCollapser::handle	(	EventHandler &	eh,
		const tPVector &	tagged,
		const Hint &	hint
	)			`[virtual]`

The main function called by the EventHandler class to perform a step.

This function simply calls the collapse() function.

Parameters:

	eh	the EventHandler in charge of the Event generation.
	tagged	if not empty these are the only particles which should be considered by the StepHandler.
	hint	a Hint object with possible information from previously performed steps.

Exceptions:

	Veto	if the StepHandler requires the current step to be discarded.
	Stop	if the generation of the current Event should be stopped after this call.
	Exception	if something goes wrong.

Implements ThePEG::StepHandler.

virtual vector<ColourSinglet> ThePEG::ClusterCollapser::collapse	(	tPVector	tagged,
		tStepPtr	newstep
	)			`[virtual]`

Perform all necessary collapses.

Return the uncollapsed clusters.

virtual SingletMap ThePEG::ClusterCollapser::getSinglets ( const tPVector & tagged ) const [virtual]

Go through the tagged partons and extract all colour singlet combination of partons.

Order them in invariant mass (minus the constituent masses of the partons).

virtual tcPDPtr ThePEG::ClusterCollapser::pickFlavour ( ) const [virtual]

Pick a random flavour.

Default version picks u,d or s with ratio 3:3:1.

virtual void ThePEG::ClusterCollapser::collapse	(	tStepPtr	newStep,
		const ColourSinglet &	cs,
		const tPVector &	tagged
	)			const `[protected, virtual]`

Perform the actual collapse of a cluster into one hadron.

Add the produced hadron to the given step as decay products of the partons in the cluster. The tagged particles are used for momentum compensation.

virtual bool ThePEG::ClusterCollapser::collapse2	(	tStepPtr	newStep,
		const ColourSinglet &	cs
	)			const `[protected, virtual]`

Perform the actual collapse of a cluster into two hadrons.

Add the produced hadrons to the given step as decay products of the partons in the cluster. The tagged particles are used for momentum compensation.

Returns:: false if the collapse failed in some way.

virtual tPVector ThePEG::ClusterCollapser::getCompensators	(	Energy	mh,
		const ColourSinglet &	cs,
		const tPVector &	tagged,
		tStepPtr	newStep
	)			const `[protected, virtual]`

Get particles for compensation.

Look through the tagged vector for particles (which are not in the colour singlet cs) which can be used to compensate momentum when cs collapses into a hadron with mass mh. These partons are then copied into the new step so that their momentum can be changed and then returned.

void ThePEG::ClusterCollapser::persistentOutput ( PersistentOStream & os ) const

Function used to write out object persistently.

Parameters:

os

the persistent output stream written to.

Reimplemented from ThePEG::Interfaced.

void ThePEG::ClusterCollapser::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 ThePEG::Interfaced.

virtual IBPtr ThePEG::ClusterCollapser::clone ( ) const [protected, virtual]

Make a simple clone of this object.

Returns:: a pointer to the new object.

Implements ThePEG::InterfacedBase.

virtual IBPtr ThePEG::ClusterCollapser::fullclone ( ) const [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.

Member Data Documentation

Energy ThePEG::ClusterCollapser::theEnergyCut [private]

Energy cut.

If the invariant mass of a cluster, minus the constituent masses of its partons is below this cut, it will be collapsed into one or two particles.

Definition at line 250 of file ClusterCollapser.h.

Referenced by cut().

Exception::Severity ThePEG::ClusterCollapser::errorlevel [protected]

How should we respond to errors? 0 means do nothing, ie.

the cluster will not be collapsed, or the momentum will not be consterved. Otherwise the severity will be what is defined in the class Exception.

Definition at line 272 of file ClusterCollapser.h.

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

ClusterCollapser.h


Public Types
typedef Ptr< FlavourGenerator > ::pointer	FlavGenPtr
	Declare a pointer to a FlavourGenerator object.
typedef multimap< Energy, ColourSinglet >	SingletMap
	Declare a multimap of singlets indexed by their mass.
Public Member Functions
virtual vector< ColourSinglet >	collapse (tPVector tagged, tStepPtr newstep)
	Perform all necessary collapses.
virtual SingletMap	getSinglets (const tPVector &tagged) const
	Go through the tagged partons and extract all colour singlet combination of partons.
virtual ColourSinglet	splitDiQuarkJunction (ColourSinglet &cs, tStepPtr newStep) const
	If a singlet contains at least one diquark and a junction, split the diquark and split off a new colour singlet.
virtual ColourSinglet	splitDiDiQuark (ColourSinglet &cs, tStepPtr newStep) const
	If a singlet contains a simple string with diquarks in both ends, split them into quarks and split off a new colour singlet.
Energy	cut () const
	If the invariant mass of a cluster, minus the constituent masses of its partons is below this cut, it will be collapsed into one or two particles.
int	nTry2 () const
	The number of attempts to collapse a cluster into two particles, before it is collapsed into one particle.
virtual tcPDPtr	pickFlavour () const
	Pick a random flavour.
Standard constructors and destructors.
	ClusterCollapser ()
	The default constructor.
virtual	~ClusterCollapser ()
	The destructor.
Virtual functions required by the StepHandler class.
virtual void	handle (EventHandler &eh, const tPVector &tagged, const Hint &hint)
	The main function called by the EventHandler class to perform a step.
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 bool	diQuarkJunction (const ColourSinglet &cs)
	Returns true iff the given singlet contains a junction and at least one diquark.
static bool	diDiQuark (const ColourSinglet &cs)
	Returns true iff the given singlet contains one string piece with diquarks in both ends.
static Energy	mass (const ColourSinglet &cl)
	Return the invariant mass of a cluster minus the constituent masses of its partons.
static void	insert (SingletMap &mmap, const ColourSinglet &cl)
	Insert a ColourSinglet object in a SingletMap.
static void	Init ()
	Standard Init function used to initialize the interfaces.
Protected Member Functions
virtual void	collapse (tStepPtr newStep, const ColourSinglet &cs, const tPVector &tagged) const
	Perform the actual collapse of a cluster into one hadron.
virtual bool	collapse2 (tStepPtr newStep, const ColourSinglet &cs) const
	Perform the actual collapse of a cluster into two hadrons.
virtual tPVector	getCompensators (Energy mh, const ColourSinglet &cs, const tPVector &tagged, tStepPtr newStep) const
	Get particles for compensation.
virtual tcPDPtr	getHadron (const ColourSinglet &cs) const
	Return a hadron into which the given cluster may collapse.
virtual tcPDPair	getHadrons (const ColourSinglet &cs) const
	Return a pair of hadrons into which the given cluster may collapse.
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 Attributes
Exception::Severity	errorlevel
	How should we respond to errors? 0 means do nothing, ie.
double	pStrange
	The relative probability to produce a s-sbar pair in a split as compared to a u-ubar or d-dbar pair.
Private Member Functions
ClusterCollapser &	operator= (const ClusterCollapser &)
	Private and non-existent assignment operator.
Private Attributes
Energy	theEnergyCut
	Energy cut.
int	theNTry2
	The number of attempts to collapse a cluster into two particles, before it is collapsed into one particle.
FlavGenPtr	flavGen
	The flavour generator object to use to combine quarks and diqurks into hadrons.
Static Private Attributes
static ClassDescription < ClusterCollapser >	initClusterCollapser
	Describe a concrete class with persistent data.