UserHooks is base class for user access to program execution. More...

#include <UserHooks.h>

Inheritance diagram for UserHooks:

Public Member Functions
virtual	~UserHooks ()
	Destructor.

virtual bool	initAfterBeams ()
	Initialisation after beams have been set by Pythia::init().

virtual bool	canModifySigma ()
	Possibility to modify cross section of process.

virtual double	multiplySigmaBy (const SigmaProcess sigmaProcessPtr, const PhaseSpace phaseSpacePtr, bool inEvent)
	Multiplicative factor modifying the cross section of a hard process. More...

virtual bool	canBiasSelection ()
	Possibility to bias selection of events, compensated by a weight.

virtual double	biasSelectionBy (const SigmaProcess sigmaProcessPtr, const PhaseSpace phaseSpacePtr, bool inEvent)
	Multiplicative factor in the phase space selection of a hard process. More...

virtual double	biasedSelectionWeight ()
	Event weight to compensate for selection weight above.

virtual bool	canVetoProcessLevel ()
	Possibility to veto event after process-level selection.

virtual bool	doVetoProcessLevel (Event &)

virtual bool	canSetLowEnergySigma (int, int) const

virtual double	doSetLowEnergySigma (int, int, double, double, double) const

virtual bool	canVetoResonanceDecays ()
	Possibility to veto resonance decay chain.

virtual bool	doVetoResonanceDecays (Event &)

virtual bool	canVetoPT ()

virtual double	scaleVetoPT ()
	Transverse-momentum scale for veto test.

virtual bool	doVetoPT (int, const Event &)

virtual bool	canVetoStep ()

virtual int	numberVetoStep ()
	Up to how many ISR + FSR steps of hardest interaction should be checked.

virtual bool	doVetoStep (int, int, int, const Event &)

virtual bool	canVetoMPIStep ()

virtual int	numberVetoMPIStep ()
	Up to how many MPI steps should be checked.

virtual bool	doVetoMPIStep (int, const Event &)

virtual bool	canVetoPartonLevelEarly ()

virtual bool	doVetoPartonLevelEarly (const Event &)

virtual bool	retryPartonLevel ()

virtual bool	canVetoPartonLevel ()
	Possibility to veto event after parton-level selection.

virtual bool	doVetoPartonLevel (const Event &)

virtual bool	canSetResonanceScale ()
	Possibility to set initial scale in TimeShower for resonance decay.

virtual double	scaleResonance (int, const Event &)

virtual bool	canVetoISREmission ()
	Possibility to veto an emission in the ISR machinery.

virtual bool	doVetoISREmission (int, const Event &, int)

virtual bool	canVetoFSREmission ()
	Possibility to veto an emission in the FSR machinery.

virtual bool	doVetoFSREmission (int, const Event &, int, bool=false)

virtual bool	canVetoMPIEmission ()
	Possibility to veto an MPI.

virtual bool	doVetoMPIEmission (int, const Event &)

virtual bool	canReconnectResonanceSystems ()
	Possibility to reconnect colours from resonance decay systems.

virtual bool	doReconnectResonanceSystems (int, Event &)

virtual bool	canChangeFragPar ()
	Can change fragmentation parameters.

virtual void	setStringEnds (const StringEnd , const StringEnd , vector< int >)

virtual bool	doChangeFragPar (StringFlav , StringZ , StringPT , int, double, vector< int >, const StringEnd )

virtual bool	doVetoFragmentation (Particle, const StringEnd *)

virtual bool	doVetoFragmentation (Particle, Particle, const StringEnd , const StringEnd )

virtual bool	canVetoAfterHadronization ()

virtual bool	doVetoAfterHadronization (const Event &)
	Do the actual veto after hadronization.

virtual bool	canSetImpactParameter () const
	Can set the overall impact parameter for the MPI treatment.

virtual double	doSetImpactParameter ()
	Set the overall impact parameter for the MPI treatment.

virtual bool	onEndHadronLevel (HadronLevel &, Event &)
	Custom processing at the end of HadronLevel::next.

Public Member Functions inherited from PhysicsBase
void	initInfoPtr (Info &infoPtrIn)
	This function is called from above for physics objects used in a run. More...

virtual	~PhysicsBase ()
	Empty virtual destructor.

bool	flag (string key) const
	Shorthand to read settings values.

int	mode (string key) const

double	parm (string key) const

string	word (string key) const

vector< bool >	fvec (string key) const

vector< int >	mvec (string key) const

vector< double >	pvec (string key) const

vector< string >	wvec (string key) const

Protected Member Functions
	UserHooks ()
	Constructor.

virtual void	onInitInfoPtr () override
	After initInfoPtr, initialize workEvent. More...

void	omitResonanceDecays (const Event &process, bool finalOnly=false)
	omitResonanceDecays omits resonance decay chains from process record. More...

void	subEvent (const Event &event, bool isHardest=true)
	subEvent extracts currently resolved partons in the hard process. More...

Protected Member Functions inherited from PhysicsBase
	PhysicsBase ()
	Default constructor.

virtual void	onBeginEvent ()
	This function is called in the very beginning of each Pythia::next call.

virtual void	onEndEvent (Status)

virtual void	onStat ()
	This function is called from the Pythia::stat() call.

void	registerSubObject (PhysicsBase &pb)
	Register a sub object that should have its information in sync with this.

Protected Attributes
Event	workEvent = {}
	Have one event object around as work area.

double	selBias = 1.
	User-imposed selection bias.

double	enhancedEventWeight = {}
	Bookkept quantities for boosted event weights.

double	pTEnhanced = {}

double	wtEnhanced = {}

Protected Attributes inherited from PhysicsBase
Info *	infoPtr = {}

Settings *	settingsPtr = {}
	Pointer to the settings database.

ParticleData *	particleDataPtr = {}
	Pointer to the particle data table.

Logger *	loggerPtr = {}
	Pointer to logger.

HadronWidths *	hadronWidthsPtr = {}
	Pointer to the hadron widths data table.

Rndm *	rndmPtr = {}
	Pointer to the random number generator.

CoupSM *	coupSMPtr = {}
	Pointers to SM and SUSY couplings.

CoupSUSY *	coupSUSYPtr = {}

BeamSetup *	beamSetupPtr = {}

BeamParticle *	beamAPtr = {}

BeamParticle *	beamBPtr = {}

BeamParticle *	beamPomAPtr = {}

BeamParticle *	beamPomBPtr = {}

BeamParticle *	beamGamAPtr = {}

BeamParticle *	beamGamBPtr = {}

BeamParticle *	beamVMDAPtr = {}

BeamParticle *	beamVMDBPtr = {}

PartonSystems *	partonSystemsPtr = {}
	Pointer to information on subcollision parton locations.

SigmaTotal *	sigmaTotPtr = {}
	Pointers to the total/elastic/diffractive cross sections.

SigmaCombined *	sigmaCmbPtr = {}

set< PhysicsBase * >	subObjects

UserHooksPtr	userHooksPtr

Additional Inherited Members
Public Types inherited from PhysicsBase
enum	Status { INCOMPLETE = -1, COMPLETE = 0, CONSTRUCTOR_FAILED, INIT_FAILED, LHEF_END, LOWENERGY_FAILED, PROCESSLEVEL_FAILED, PROCESSLEVEL_USERVETO, MERGING_FAILED, PARTONLEVEL_FAILED, PARTONLEVEL_USERVETO, HADRONLEVEL_FAILED, CHECK_FAILED, OTHER_UNPHYSICAL, HEAVYION_FAILED, HADRONLEVEL_USERVETO }
	Enumerate the different status codes the event generation can have.

Detailed Description

UserHooks is base class for user access to program execution.

Member Function Documentation

double biasSelectionBy	(	const SigmaProcess *	sigmaProcessPtr,
		const PhaseSpace *	phaseSpacePtr,
		bool	inEvent
	)

virtual

Multiplicative factor in the phase space selection of a hard process.

biasSelectionBy allows the user to introduce a multiplicative factor that modifies the cross section of a hard process. The event is assigned a wegith that is the inverse of the selection bias, such that the cross section is unchanged. Since it is called from before the event record is generated in full, the normal analysis does not work. The code here provides a rather extensive summary of which methods actually do work. It is a convenient starting point for writing your own derived routine.

Process code, necessary when some to be treated differently. int code = sigmaProcessPtr->code();

Final multiplicity, i.e. whether 2 -> 1 or 2 -> 2. int nFinal = sigmaProcessPtr->nFinal();

Incoming x1 and x2 to the hard collision, and factorization scale. double x1 = phaseSpacePtr->x1(); double x2 = phaseSpacePtr->x2(); double Q2Fac = sigmaProcessPtr->Q2Fac();

Renormalization scale and assumed alpha_strong and alpha_EM. double Q2Ren = sigmaProcessPtr->Q2Ren(); double alphaS = sigmaProcessPtr->alphaSRen(); double alphaEM = sigmaProcessPtr->alphaEMRen();

Subprocess mass-square. double sHat = phaseSpacePtr->sHat();

Now methods only relevant for 2 -> 2. if (nFinal == 2) {

Mandelstam variables and hard-process pT. double tHat = phaseSpacePtr->tHat(); double uHat = phaseSpacePtr->uHat(); double pTHat = phaseSpacePtr->pTHat();

Masses of the final-state particles. (Here 0 for light quarks.) double m3 = sigmaProcessPtr->m(3); double m4 = sigmaProcessPtr->m(4);

}

Insert here your calculation of the selection bias. Here illustrated by a weighting up of events at high pT. selBias = pow4(phaseSpacePtr->pTHat());

Return the selBias weight. Warning: if you use another variable than selBias the compensating weight will not be set correctly. return selBias;

Dummy statement to avoid compiler warnings.

Reimplemented in UserHooksVector.

virtual bool canSetLowEnergySigma	(	int	,
		int
	)		const

inlinevirtual

Possibility to set low energy cross sections. Usage: canSetLowEnergySigma(idA, idB).

virtual bool canVetoAfterHadronization ( )

inlinevirtual

Possibility to veto an event after hadronization based on event contents. Works as an early trigger to avoid running the time consuming rescattering process on uninteresting events.

Reimplemented in UserHooksVector.

virtual bool canVetoMPIStep ( )

inlinevirtual

Possibility to veto MPI + ISR + FSR evolution and kill event, making decision after fixed number of MPI steps.

Reimplemented in UserHooksVector, and PowhegHooks.

virtual bool canVetoPartonLevelEarly ( )

inlinevirtual

Possibility to veto event after ISR + FSR + MPI in parton level, but before beam remnants and resonance decays.

Reimplemented in UserHooksVector, JetMatching, JetMatchingMadgraphInputAlpgen, and JetMatchingAlpgenInputAlpgen.

virtual bool canVetoPT ( )

inlinevirtual

Possibility to veto MPI + ISR + FSR evolution and kill event, making decision at a fixed pT scale. Useful for MLM-style matching.

Reimplemented in UserHooksVector.

virtual bool canVetoStep ( )

inlinevirtual

Possibility to veto MPI + ISR + FSR evolution and kill event, making decision after fixed number of ISR or FSR steps.

Reimplemented in UserHooksVector, JetMatchingMadgraph, and JetMatching.

virtual bool doChangeFragPar	(	StringFlav *	,
		StringZ *	,
		StringPT *	,
		int	,
		double	,
		vector< int >	,
		const StringEnd *
	)

inlinevirtual

Do change fragmentation parameters. Input: flavPtr, zPtr, pTPtr, idEnd, m2Had, iParton and posEnd (or negEnd).

Reimplemented in UserHooksVector.

virtual bool doReconnectResonanceSystems	(	int	,
		Event &
	)

inlinevirtual

Do reconnect colours from resonance decay systems. Usage: doVetoFSREmission( oldSizeEvt, event) where oldSizeEvent is the event size before resonance decays. Should normally return true, while false means serious failure. Value of PartonLevel:earlyResDec determines where method is called.

Reimplemented in TopReconUserHooks, UserHooksVector, and MBReconUserHooks.

virtual double doSetLowEnergySigma	(	int	,
		int	,
		double	,
		double	,
		double
	)		const

inlinevirtual

Set low energy cross sections for ids where canSetLowEnergySigma is true. Usage: doSetLowEnergySigma(idA, idB, eCM, mA, mB).

virtual bool doVetoFragmentation	(	Particle	,
		const StringEnd *
	)

inlinevirtual

Do a veto on a hadron just before it is added to the final state. The StringEnd from which the the hadron was produced is included for information.

Reimplemented in UserHooksVector.

virtual bool doVetoFragmentation	(	Particle	,
		Particle	,
		const StringEnd *	,
		const StringEnd *
	)

inlinevirtual

Do a veto on a hadron just before it is added to the final state (final two hadron case).

Reimplemented in UserHooksVector.

virtual bool doVetoFSREmission	(	int	,
		const Event &	,
		int	,
		bool	= `false`
	)

inlinevirtual

Decide whether to veto current emission or not, based on event record. Usage: doVetoFSREmission( sizeOld, event, iSys, inResonance) where sizeOld is size of event record before current emission-to-be-scrutinized was added, iSys is the system of the radiation (according to PartonSystems), and inResonance is true if the emission takes place in a resonance decay.

Reimplemented in VinciaEWVetoHook, PowhegHooks, and UserHooksVector.

virtual bool doVetoISREmission	(	int	,
		const Event &	,
		int
	)

inlinevirtual

Decide whether to veto current emission or not, based on event record. Usage: doVetoISREmission( sizeOld, event, iSys) where sizeOld is size of event record before current emission-to-be-scrutinized was added, and iSys is the system of the radiation (according to PartonSystems).

Reimplemented in VinciaEWVetoHook, UserHooksVector, and PowhegHooks.

virtual bool doVetoMPIEmission	(	int	,
		const Event &
	)

inlinevirtual

Decide whether to veto an MPI based on event record. Usage: doVetoMPIEmission( sizeOld, event) where sizeOld is size of event record before the current MPI.

Reimplemented in PowhegHooks, and UserHooksVector.

virtual bool doVetoMPIStep	(	int	,
		const Event &
	)

inlinevirtual

Decide whether to veto current event or not, based on event record. Usage: doVetoMPIStep( nMPI, event), where nMPI is number of MPI's so far.

Reimplemented in UserHooksVector, and PowhegHooks.

virtual bool doVetoPartonLevel ( const Event & )

inlinevirtual

Decide whether to veto current partons or not, based on event record. Usage: doVetoPartonLevel( event).

Reimplemented in UserHooksVector.

virtual bool doVetoPartonLevelEarly ( const Event & )

inlinevirtual

Decide whether to veto current partons or not, based on event record. Usage: doVetoPartonLevelEarly( event).

Reimplemented in UserHooksVector, JetMatching, JetMatchingMadgraphInputAlpgen, and JetMatchingAlpgenInputAlpgen.

virtual bool doVetoProcessLevel ( Event & )

inlinevirtual

Decide whether to veto current process or not, based on process record. Usage: doVetoProcessLevel( process).

Reimplemented in UserHooksVector, JetMatchingMadgraph, JetMatching, JetMatchingMadgraphInputAlpgen, JetMatchingAlpgenInputAlpgen, amcnlo_unitarised_interface, and SetLHEDecayProductHook.

virtual bool doVetoPT	(	int	,
		const Event &
	)

inlinevirtual

Decide whether to veto current event or not, based on event record. Usage: doVetoPT( iPos, event), where iPos = 0: no emissions so far; iPos = 1/2/3 joint evolution, latest step was MPI/ISR/FSR; iPos = 4: FSR only afterwards; iPos = 5: FSR in resonance decay.

Reimplemented in UserHooksVector.

virtual bool doVetoResonanceDecays ( Event & )

inlinevirtual

Decide whether to veto current resonance decay chain or not, based on process record. Usage: doVetoProcessLevel( process).

Reimplemented in UserHooksVector, and ResonanceDecayFilterHook.

virtual bool doVetoStep	(	int	,
		int	,
		int	,
		const Event &
	)

inlinevirtual

Decide whether to veto current event or not, based on event record. Usage: doVetoStep( iPos, nISR, nFSR, event), where iPos as above, nISR and nFSR number of emissions so far for hard interaction only.

Reimplemented in UserHooksVector, JetMatchingMadgraph, and JetMatching.

double multiplySigmaBy	(	const SigmaProcess *	sigmaProcessPtr,
		const PhaseSpace *	phaseSpacePtr,
		bool	inEvent
	)

virtual

Multiplicative factor modifying the cross section of a hard process.

The UserHooks class.

multiplySigmaBy allows the user to introduce a multiplicative factor that modifies the cross section of a hard process. Since it is called from before the event record is generated in full, the normal analysis does not work. The code here provides a rather extensive summary of which methods actually do work. It is a convenient starting point for writing your own derived routine.

Process code, necessary when some to be treated differently. int code = sigmaProcessPtr->code();

Final multiplicity, i.e. whether 2 -> 1 or 2 -> 2. int nFinal = sigmaProcessPtr->nFinal();

Incoming x1 and x2 to the hard collision, and factorization scale. double x1 = phaseSpacePtr->x1(); double x2 = phaseSpacePtr->x2(); double Q2Fac = sigmaProcessPtr->Q2Fac();

Renormalization scale and assumed alpha_strong and alpha_EM. double Q2Ren = sigmaProcessPtr->Q2Ren(); double alphaS = sigmaProcessPtr->alphaSRen(); double alphaEM = sigmaProcessPtr->alphaEMRen();

Subprocess mass-square. double sHat = phaseSpacePtr->sHat();

Now methods only relevant for 2 -> 2. if (nFinal == 2) {

Mandelstam variables and hard-process pT. double tHat = phaseSpacePtr->tHat(); double uHat = phaseSpacePtr->uHat(); double pTHat = phaseSpacePtr->pTHat();

Masses of the final-state particles. (Here 0 for light quarks.) double m3 = sigmaProcessPtr->m(3); double m4 = sigmaProcessPtr->m(4);

}

Dummy statement to avoid compiler warnings.

Reimplemented in UserHooksVector, and SuppressSmallPT.

void omitResonanceDecays	(	const Event &	process,
		bool	finalOnly = `false`
	)

protected

omitResonanceDecays omits resonance decay chains from process record.

Reset work event to be empty

Loop through all partons. Beam particles should be copied.

Daughters of beams should normally be copied.

Granddaughters of beams should normally be copied and are final.

Optionally non-final are not copied.

Do copying and modify status/daughters of final.

When final only : no mothers; position in full event as daughters.

virtual void onInitInfoPtr ( )

inlineoverrideprotectedvirtual

After initInfoPtr, initialize workEvent.

Set smart pointer to null, in order to avoid circular dependency

Reimplemented from PhysicsBase.

virtual bool retryPartonLevel ( )

inlinevirtual

Retry same ProcessLevel with a new PartonLevel after a veto in doVetoPT, doVetoStep, doVetoMPIStep or doVetoPartonLevelEarly if you overload this method to return true.

Reimplemented in UserHooksVector.

virtual double scaleResonance	(	int	,
		const Event &
	)

inlinevirtual

Initial scale for TimeShower evolution. Usage: scaleResonance( iRes, event), where iRes is location of decaying resonance in the event record.

Reimplemented in MergeResScaleHook, and UserHooksVector.

virtual void setStringEnds	(	const StringEnd *	,
		const StringEnd *	,
		vector< int >
	)

inlinevirtual

Set initial ends of a string to be fragmented. This is done once for each string. Note that the second string end may be zero in case we are hadronising a string piece leading to a junction.

Reimplemented in UserHooksVector.

void subEvent	(	const Event &	event,
		bool	isHardest = `true`
	)

protected

subEvent extracts currently resolved partons in the hard process.

Reset work event to be empty.

At the PartonLevel final partons are bookkept by subsystem.

Find which subsystem to study.

Loop through all the final partons of the given subsystem.

Copy partons to work event.

No mothers. Position in full event as daughters.

At the ProcessLevel no subsystems have been defined.

Loop through all partons, and copy all final ones.

No mothers. Position in full event as daughters.

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

include/Pythia8/UserHooks.h
src/UserHooks.cc

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Function Documentation