ThePEG  1.8.0
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ThePEG::PartonExtractor Class Reference

The PartonExtractor is a base class defining the interface to objects responsible for extracting partons from particles. More...

#include <PartonExtractor.h>

Inheritance diagram for ThePEG::PartonExtractor:
Inheritance graph
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List of all members.

Public Types

typedef map< cPPtr, PBIPtrPartonBinInstanceMap
 A map of PartonBinInstance objects indexed by the extracted parton.
- Public Types inherited from ThePEG::LastXCombInfo<>
typedef ThePEG::Ptr< XComb >
::pointer 
XCPtr
 Alias for a reference counted pointer to XC .
typedef ThePEG::Ptr< XComb >
::const_pointer 
cXCPtr
 Alias for a reference counted pointer to a const XC .
typedef ThePEG::Ptr< XComb >
::transient_pointer 
tXCPtr
 Alias for a transient pointer to XC .
typedef ThePEG::Ptr< XComb >
::transient_const_pointer 
tcXCPtr
 Alias for a transient pointer to a const XC .

Public Member Functions

int maxTries () const
 The maximum number of attempts allowed when trying to generate remnants.
tcPDFPtr getPDF (tcPDPtr particle) const
 Return the PDFBase object to be used for the incoming particle type.
Standard constructors and destructors.
 PartonExtractor ()
 Default constructor.
virtual ~PartonExtractor ()
 Destructor.
Virtual functions which may be overridden in sub-classes.
virtual bool canHandle (const cPDPair &)
 Return true if this parton extractor can handle the given types of incoming particles.
virtual PartonPairVec getPartons (Energy maxEnergy, const cPDPair &, const Cuts &) const
 Return a vector of possible pairs of parton bins which can be produced within a given maximum total particle-particle invariant mass squared, maxEnergy sBin.
virtual Energy2 newScale ()
 May be overriden by sub-classes which have their own oppinion about what scale to use in a hard subprocess.
virtual void colourConnect (tPPtr particle, tPPtr parton, const tPVector &remnants) const
 Connect the remnants with the colour lines of the extracted parton.
virtual PBIPair newRemnants (tPPair oldp, tPPair newp, tStepPtr step)
 If remnants has already been created for the given parton, remove them from the given step and generate new remnants corresponding to the parton newp and add them to the step.
virtual pair< int, int > nDims (const PBPair &pbins)
 
Determine the number of random numbers needed to calculate

$\hat{s}$ and the product of all densitiy functions.

virtual void prepare (const PBIPair &pbins)
 Prepare the given parton bin instances for generating a new event.
virtual bool generateL (const PBIPair &pbins, const double *r1, const double *r2)
 Generate $l=\log(1/x)$ for all parton extractions.
virtual void generateL (PartonBinInstance &pb, const double *r)
 Used by generateL() for each of the final parton bins.
virtual Energy2 generateSHat (Energy2 s, const PBIPair &pbins, const double *r1, const double *r2, bool mepartons=false)
 
Generate the rest of the degrees of freedom to calculate

$\hat{s}$ and the product of all densitiy functions.

virtual double fullFn (const PBIPair &pbins, Energy2 scale, pair< bool, bool > noLastPDF=make_pair(false, false))
 Return the product of all density functions.
virtual void construct (const PBIPair &pbins, tStepPtr step) const
 Construct remnants and add them to the step.
virtual void constructRemnants (const PBIPair &pbins, tSubProPtr sub, tStepPtr step) const
 Construct remnants for partons created outside of this extractor.
virtual LorentzRotation boostRemnants (PBIPair &bins, LorentzMomentum k1, LorentzMomentum k2, bool side1, bool side2) const
 Get boost for hard subsystem and boost remnants.
Access information about the current paron extraction.
tPBIPtr partonBinInstance (tcPPtr) const
 Return the corresponding parton bin instance for a given extracted parton.
void select (tXCombPtr newXComb)
 Set the XComb object describing the current hard sub-process.
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.
- Public Member Functions inherited from ThePEG::LastXCombInfo<>
const XComblastXComb () const
 Return a reference to the last selected XComb.
tXCPtr lastXCombPtr () const
 Return a pointer to the last selected XComb.
const XComblastHeadXComb () const
 If the last selected XComb object belongs to a group of XComb's return a reference to the head XComb object for this group.
tXCPtr lastHeadXCombPtr () const
 If the last selected XComb object belongs to a group of XComb's return a pointer to the head XComb object for this group.
const EventHandlerlastEventHandler () const
 Return a reference to the currently used EventHandler.
tPExtrPtr lastExtractor () const
 A pointer to the currently used parton extractor.
PDFT pdf (tcPPtr parton) const
 Return the parton density used to extract the given parton.
const CutslastCuts () const
 A reference to the currently used kinematical cuts.
tCutsPtr lastCutsPtr () const
 A pointer to the currently used kinematical cuts.
const PPairlastParticles () const
 Return the pair of incoming parton instances.
Energy2 lastS () const
 The last generated total energy squared of the incoming particles.
const PPairlastPartons () const
 Return the pair of incoming parton instances.
Energy2 lastSHat () const
 The last used interval in total parton-parton energy squared.
double lastTau () const
 Return lastSHat()/lastS().
double lastY () const
 The generated rapidity of the hard scattering sub-system.
double lastP1 () const
 Log of one over the momentum fraction of the first incoming particle w.r.t.
double lastP2 () const
 Log of one over the momentum fraction of the second incoming particle w.r.t.
double lastL1 () const
 Log of one over the first incoming parton momentum fraction w.r.t.
double lastL2 () const
 Log of one over the second incoming parton momentum fraction w.r.t.
double lastX1 () const
 The first incoming parton momentum fraction w.r.t.
double lastX2 () const
 The second incoming parton momentum fraction w.r.t.
double lastE1 () const
 Return 1-lastX1() to highest possible precision for x $\rightarrow$ 1.
double lastE2 () const
 Return 1-lastX2() to highest possible precision for x $\rightarrow$ 1.
double lastFL1L2 () const
 The product of the parton density functions at the last generated phase-space point.
Energy2 lastScale () const
 The chosen scale of the hard scattering.
double lastAlphaS () const
 Get the $\alpha_S$ used in the hard scattering.
double lastAlphaEM () const
 Get the $\alpha_{EM}$ used in the hard scattering.
const vector< Lorentz5Momentum > & meMomenta () const
 Return the momenta of the incoming and outgoing partons to be used by the matrix element object, in the order specified by the TreeDiagram objects given by the matrix element.
double lastME2 () const
 Return the matrix element squared as calculated for the last phase space point.
double jacobian () const
 Get the last jacobian obtained when generating the kinematics for the call to dSigHatDR.
CrossSection lastMECrossSection () const
 Return the partonic cross section as calculated for the last phase space point.
double lastMEPDFWeight () const
 Return the PDF weight as calculated for the last phase space point, if the matrix element does supply PDF weights.
tSubProPtr subProcess () const
 Return the SubProcess object corresponding to the last generated sub-process.
const cPDVectormePartonData () const
 Return the incoming and outgoing parton types to be used by the matrix element object, in the order specified by the TreeDiagram objects given by the matrix element.

Static Public Member Functions

static void Init ()
 Standard Init function used to initialize the interface.

Protected Member Functions

virtual void addPartons (tPBPtr incoming, const PDFCuts &cuts, tcPDFPtr pdf, PartonVector &pbins) const
 Add parton bins to pbins for the given incoming particle and the specified cuts.
tcPDFPtr noPDF () const
 The NoPDF object.
template<typename Iterator >
void findConnect (tColinePtr line, tPPtr parton, bool anti, Iterator first, Iterator last) const
 Connect the first (anti) coloured particle in the given range (not equal to parton) and connect it to the colour line.
Functions used by the main virtual functions. Some of

these may be overridden in sub-classes.

virtual bool generate (PartonBinInstance &pb, const double *r, Energy2 shat, const Lorentz5Momentum &first, bool haveMEPartons=false)
 Used by generateSHat() for each of the final parton bins.
virtual double fullFn (const PartonBinInstance &pb, bool noLastPDF=false)
 Used by the public fullFn() for each of the final parton bins.
virtual void construct (PartonBinInstance &pb, tStepPtr step, bool boost=true) const
 Used by the public construct() for each of the final parton bins.
PBIPtr newRemnants (tPBIPtr oldpb, tPPtr newp, const LorentzMomentum &k)
 Used by the public newRemnants() for each of the parton bins.
void addNewRemnants (tPBIPtr oldpb, tPBIPtr newpb, tStepPtr step)
 Used by the public newRemnants() for each of the parton bins.
virtual void transformRemnants (LorentzMomentum &Ph, LorentzMomentum &Pr, const LorentzMomentum &k, const LorentzMomentum &P) const
 Transform remnant momentum.
virtual void constructRemnants (PartonBinInstance &pb, LorentzMomentum &Ph, const LorentzMomentum &k) const
 Construct remnants recursively for the parton represented by pb.
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 dofinish ()
 Finalize this object.

Private Member Functions

PartonExtractoroperator= (const PartonExtractor &)
 Private and non-existent assignment operator.

Private Attributes

PartonBinInstanceMap partonBinInstances
 The PartonBinInstance's used mapped to the respective partons.
vector< PDFPtrtheSpecialDensities
 A list of special PDFBase objects to be used.
PDFPtr theFirstPDF
 PDFBase object to override first PDF.
PDFPtr theSecondPDF
 PDFBase object to override second PDF.
PDFPtr theNoPDF
 The NoPDF object.
int theMaxTries
 The maximum number of tries allowed when trying to produce remnants.
bool flatSHatY
 True if this extractor should override the $l$-generation in the PDFs and generate a flat distribution in $\log(\hat{s})$ and y.

Static Private Attributes

static ClassDescription
< PartonExtractor
initPartonExtractor
 Describe a concrete class with persistent data.

Friends

class XComb
 XComb is a friend.

Additional Inherited Members

- Protected Attributes inherited from ThePEG::LastXCombInfo<>
XCPtr theLastXComb
 The pointer to the last selected XComb.

Detailed Description

The PartonExtractor is a base class defining the interface to objects responsible for extracting partons from particles.

It is used by a SubProcessHandler which combines one PartonExtractor with a number of MEBase objects which are the used in an XComb in a StandardEventHandler to generate hard sub-processes.

PartonExtractor inherits from the general HandlerBase class and from the LastXCombInfo class to have easy acces to information about the currently chosen hard sub-process.

See also:
The interfaces defined for PartonExtractor.
SubProcessHandler
MEBase
EventHandler
StandardEventHandler
XComb
HandlerBase

Definition at line 44 of file PartonExtractor.h.


Member Typedef Documentation

A map of PartonBinInstance objects indexed by the extracted parton.

Definition at line 52 of file PartonExtractor.h.


Member Function Documentation

virtual LorentzRotation ThePEG::PartonExtractor::boostRemnants ( PBIPair bins,
LorentzMomentum  k1,
LorentzMomentum  k2,
bool  side1,
bool  side2 
) const
virtual

Get boost for hard subsystem and boost remnants.

To be called after re-constructing remnants and obtaining new momenta of the partons entering the hard subsystem, but ignoring detailed energy and momentum conservation. Perform boosts of the remnants to conserve energy and momentum and return the boost needed for the hard subsystem. bins contains the current state of the incoming partons, including the momenta obtained after the remnant generation. k1 and k2 contains the momenta of the incoming partons before the remnant generation. If either side has no new remnants, side1 and/or side2 should be false.

virtual IBPtr ThePEG::PartonExtractor::clone ( ) const
protectedvirtual

Make a simple clone of this object.

Returns:
a pointer to the new object.

Implements ThePEG::InterfacedBase.

virtual void ThePEG::PartonExtractor::construct ( PartonBinInstance pb,
tStepPtr  step,
bool  boost = true 
) const
protectedvirtual

Used by the public construct() for each of the final parton bins.

If boost is false, no boost is necessary to give the remnants proper momenta.

virtual void ThePEG::PartonExtractor::constructRemnants ( const PBIPair pbins,
tSubProPtr  sub,
tStepPtr  step 
) const
virtual

Construct remnants for partons created outside of this extractor.

Information about the incoming partons should be set in pbins and the hard subprocess should be present in sub. Generated remnants will be added to the step.

Exceptions:
Vetoif remnant generation failed for whatever reason.
virtual void ThePEG::PartonExtractor::constructRemnants ( PartonBinInstance pb,
LorentzMomentum Ph,
const LorentzMomentum k 
) const
protectedvirtual

Construct remnants recursively for the parton represented by pb.

Used by constructRemnants(const PBIPair &, tSubProPtr, tStepPtr). Shift the momentum, Ph, of the hard subsystem to conserve energy and momentum if necessary. The momentum, k, of the parton coming into the hard subsystem from the other side is given for information. Note that Direction<0> must be set to determine if the parent particle is to be assumed to go in the positive or negative direction.

Exceptions:
Vetoif remnant generation failed for whatever reason.
virtual void ThePEG::PartonExtractor::dofinish ( )
protectedvirtual

Finalize this object.

Called in the run phase just after a run has ended. Used eg. to write out statistics.

Reimplemented from ThePEG::InterfacedBase.

virtual IBPtr ThePEG::PartonExtractor::fullclone ( ) const
protectedvirtual

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.

virtual double ThePEG::PartonExtractor::fullFn ( const PBIPair pbins,
Energy2  scale,
pair< bool, bool >  noLastPDF = make_pair(false, false) 
)
virtual

Return the product of all density functions.

If noLastPDF.first (.second) is true, then the PDF value multiplied by the momentum fraction for the last extracted parton from the first (second) incoming particle will be excluded.

virtual bool ThePEG::PartonExtractor::generate ( PartonBinInstance pb,
const double *  r,
Energy2  shat,
const Lorentz5Momentum first,
bool  haveMEPartons = false 
)
protectedvirtual

Used by generateSHat() for each of the final parton bins.

Direction<0> is set to positive(negative) for the first(second) final bin, pb. Should ask the remnant handler to generate what is needed to construct the extracted parton momentum. r is a pointer to an array of random numbers to be used and shat is the approximate invariant mass squared of the hard system produced by the extracted parton and the primary parton from the other side. first is the momentum of the original incoming particle.

Returns:
false if no remnants could be generated.
virtual void ThePEG::PartonExtractor::generateL ( PartonBinInstance pb,
const double *  r 
)
virtual

Used by generateL() for each of the final parton bins.

Direction<0> is set to positive(negative) for the first(second) final bin.

tcPDFPtr ThePEG::PartonExtractor::getPDF ( tcPDPtr  particle) const

Return the PDFBase object to be used for the incoming particle type.

If one of theSpecialDensities matches the particle type it is returned, otherwise if particle is a BeamParticleData use the PDFBase object specified there. If also this fails, return a NoPDF object.

virtual PBIPair ThePEG::PartonExtractor::newRemnants ( tPPair  oldp,
tPPair  newp,
tStepPtr  step 
)
virtual

If remnants has already been created for the given parton, remove them from the given step and generate new remnants corresponding to the parton newp and add them to the step.

The new parton bins are returned.

Exceptions:
Vetoif remnant generation failed for whatever reason.
PBIPtr ThePEG::PartonExtractor::newRemnants ( tPBIPtr  oldpb,
tPPtr  newp,
const LorentzMomentum k 
)
protected

Used by the public newRemnants() for each of the parton bins.

Exceptions:
Vetoif remnant generation failed for whatever reason.
virtual Energy2 ThePEG::PartonExtractor::newScale ( )
virtual

May be overriden by sub-classes which have their own oppinion about what scale to use in a hard subprocess.

The default version simply returns the previously selected scale.

void ThePEG::PartonExtractor::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.

Reimplemented from ThePEG::Interfaced.

void ThePEG::PartonExtractor::persistentOutput ( PersistentOStream os) const

Function used to write out object persistently.

Parameters:
osthe persistent output stream written to.

Reimplemented from ThePEG::Interfaced.

virtual void ThePEG::PartonExtractor::transformRemnants ( LorentzMomentum Ph,
LorentzMomentum Pr,
const LorentzMomentum k,
const LorentzMomentum P 
) const
protectedvirtual

Transform remnant momentum.

Assuming remnants have been generated with momentum Pr without considering energy-momentum conservation, shift the momentum, possibly compensating with the momentum of the hard subsystem, Ph. For information the momentum of the parton entering the hard subsystem from the other side, k, and the momentum of the remnants parent particle , P is given. Note that Direction<0> must be set to determine if the parent particle is to be assumed to go in the positive or negative direction.


Friends And Related Function Documentation

friend class XComb
friend

XComb is a friend.

Definition at line 47 of file PartonExtractor.h.


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