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DireMerging Class Reference

#include <DireMerging.h>

Inheritance diagram for DireMerging:
Merging PhysicsBase

Public Member Functions

 DireMerging ()
 Constructor. More...
 
void setWeightsPtr (DireWeightContainer *wgtsIn)
 
void setShowerPtrs (shared_ptr< DireTimes > timesPtr, shared_ptr< DireSpace > spacePtr)
 
void initPtrs (DireWeightContainer *wgtsIn, shared_ptr< DireTimes > timesPtr, shared_ptr< DireSpace > spacePtr, DireInfo *direInfoIn)
 
 ~DireMerging ()
 Destructor.
 
virtual void init ()
 Initialisation function for internal use inside Pythia source code. More...
 
void reset ()
 
virtual void statistics ()
 Function to print statistics. More...
 
virtual int mergeProcess (Event &process)
 Functions that implement matrix element merging. More...
 
void getSudakovs (double &wt) const
 Return CKKW-L weight.
 
void getASratios (double &wt) const
 
void getPDFratios (double &wt) const
 
void getSudakovExp (int order, double &wt) const
 
void getASratioExp (int order, double &wt) const
 
void getPDFratioExp (int order, double &wt) const
 
void clearInfos ()
 
void storeInfos ()
 
vector< double > getStoppingScales ()
 
vector< double > getStartingScales ()
 
void getStoppingInfo (double scales[100][100], double masses[100][100])
 
double generateSingleSudakov (double pTbegAll, double pTendAll, double m2dip, int idA, int type, double s=-1., double x=-1.)
 
vector< double > getSignalProb (string key)
 
vector< double > getBkgrndProb (string key)
 
vector< double > getTotalProb ()
 
void clearClassifier ()
 
- Public Member Functions inherited from Merging
 Merging ()
 Constructor.
 
virtual ~Merging ()
 Destructor.
 
void initPtrs (MergingHooksPtr mergingHooksPtrIn, PartonLevel *trialPartonLevelPtrIn)
 Initialisation function for internal use inside Pythia source code.
 
- 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
 

Public Attributes

shared_ptr< DireTimesfsr
 
shared_ptr< DireSpaceisr
 
DireInfodireInfoPtr
 
vector< double > stoppingScalesSave
 
vector< double > startingScalesSave
 
vector< double > mDipSave
 
vector< int > radSave
 
vector< int > emtSave
 
vector< int > recSave
 
vector< double > totalProbSave
 
map< string, vector< double > > signalProbSave
 
map< string, vector< double > > bkgrndProbSave
 

Protected Member Functions

int mergeProcessCKKWL (Event &process)
 Function to perform CKKW-L merging on the event. More...
 
int mergeProcessUMEPS (Event &process)
 Function to perform UMEPS merging on the event. More...
 
int mergeProcessNL3 (Event &process)
 Function to perform NL3 NLO merging on the event. More...
 
int mergeProcessUNLOPS (Event &process)
 Function to perform UNLOPS merging on the event. More...
 
bool cutOnProcess (Event &process)
 Function to apply the merging scale cut on an input event. More...
 
int calculate (Event &process)
 Function to perform CKKW-L merging on the event.
 
bool generateHistories (const Event &process, bool orderedOnly=true)
 Function to set up all histories for an event. More...
 
void tagHistories ()
 
double getPathIndex (bool useAll=false)
 
int calculateWeights (double RNpath, bool useAll=false)
 Function to calulate the weights used for UNLOPS merging. More...
 
int getStartingConditions (double RNpath, Event &process)
 Function to perform UNLOPS merging on this event. More...
 
void setSudakovs (double wt)
 
void setASratios (double wt)
 
void setPDFratios (double wt)
 
void setSudakovExp (vector< double > wts)
 
void setASratioExp (vector< double > wts)
 
void setPDFratiosExp (vector< double > wts)
 
void clearSubtractions ()
 
void appendSubtraction (double wt, const Event &event)
 
bool calculateSubtractions ()
 Function to set up all histories for an event. More...
 
bool generateUnorderedPoint (Event &process)
 Function to steer different merging prescriptions. More...
 
- Protected Member Functions inherited from Merging
int mergeProcessCKKWL (Event &process)
 Function to perform CKKW-L merging on the event. More...
 
int mergeProcessUMEPS (Event &process)
 Function to perform UMEPS merging on the event. More...
 
int mergeProcessNL3 (Event &process)
 Function to perform NL3 NLO merging on the event. More...
 
int mergeProcessUNLOPS (Event &process)
 Function to perform UNLOPS merging on the event. More...
 
bool cutOnProcess (Event &process)
 Function to apply the merging scale cut on an input event. More...
 
- Protected Member Functions inherited from PhysicsBase
 PhysicsBase ()
 Default constructor.
 
virtual void onInitInfoPtr ()
 
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

DireHistorymyHistory
 
double sudakovs
 
double asRatios
 
double pdfRatios
 
vector< double > sudakovsExp
 
vector< double > asRatiosExp
 
vector< double > pdfRatiosExp
 
vector< pair< double, Event > > subtractions
 
DireWeightContainerpsweights
 
double sum_time_1
 
double sum_time_2
 
int sum_paths
 
bool enforceCutOnLHE
 
bool doMOPS
 
bool applyTMSCut
 
bool doMerging
 
bool usePDF
 
bool allowReject
 
bool doMECs
 
bool doMEM
 
bool doGenerateSubtractions
 
bool doGenerateMergingWeights
 
bool doExitAfterMerging
 
bool allowIncompleteReal
 
int nQuarksMerge
 
bool first
 
- Protected Attributes inherited from Merging
PartonLeveltrialPartonLevelPtr
 Pointer to trial PartonLevel object.
 
MergingHooksPtr mergingHooksPtr
 Pointer to trial MergingHooks object.
 
double tmsNowMin
 Minimal value found for the merging scale in events. More...
 
- Protected Attributes inherited from PhysicsBase
InfoinfoPtr = {}
 
SettingssettingsPtr = {}
 Pointer to the settings database.
 
ParticleDataparticleDataPtr = {}
 Pointer to the particle data table.
 
HadronWidthshadronWidthsPtr = {}
 Pointer to the hadron widths data table.
 
RndmrndmPtr = {}
 Pointer to the random number generator.
 
CoupSMcoupSMPtr = {}
 Pointers to SM and SUSY couplings.
 
CoupSUSYcoupSUSYPtr = {}
 
BeamParticlebeamAPtr = {}
 
BeamParticlebeamBPtr = {}
 
BeamParticlebeamPomAPtr = {}
 
BeamParticlebeamPomBPtr = {}
 
BeamParticlebeamGamAPtr = {}
 
BeamParticlebeamGamBPtr = {}
 
BeamParticlebeamVMDAPtr = {}
 
BeamParticlebeamVMDBPtr = {}
 
PartonSystemspartonSystemsPtr = {}
 Pointer to information on subcollision parton locations.
 
SigmaTotalsigmaTotPtr = {}
 Pointer to the total/elastic/diffractive cross sections.
 
set< PhysicsBase * > subObjects
 
UserHooksPtr userHooksPtr
 

Friends

class Pythia
 

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
}
 Enumerate the different status codes the event generation can have.
 
- Static Protected Attributes inherited from Merging
static const double TMSMISMATCH = 1.5
 The Merging class. More...
 

Detailed Description

Merging is a wrapper class for the interface of matrix element merging and Pythia8.

Constructor & Destructor Documentation

DireMerging ( )
inline

Constructor.

= doMcAtNloDelta

Member Function Documentation

bool calculateSubtractions ( )
protected

Function to set up all histories for an event.

Store shower subtractions.

Need to reattach resonance decays, if necessary.

Reset hard process candidates (changed after clustering a parton).

Check if resonance structure has been changed (e.g. because of clustering W/Z/gluino)

Compare old and new resonances

If necessary, reattach resonance decay products.

Switch from 4pi to 8pi convention

Get clustering variables.

For II dipoles, scale with 1/xCS.

Multiply with ME correction.

Attach point to list of shower subtractions.

Restore stored hard process candidates

Done

int calculateWeights ( double  RNpath,
bool  useAll = false 
)
protected

Function to calulate the weights used for UNLOPS merging.

Initialise which part of UNLOPS merging is applied.

Save number of looping steps

Ensure that merging hooks to not remove emissions

Reset weight of the event.

Reset the O(alphaS)-term of the UMEPS weight.

Check if event passes the merging scale cut.

Get merging scale in current event.

Calculate number of clustering steps

Too few steps can be possible if a chain of resonance decays has been removed. In this case, reject this event, since it will be handled in lower-multiplicity samples.

Reset the minimal tms value, if necessary.

Do not apply cut if the configuration could not be projected onto an underlying born configuration.

Enfore merging scale cut if the event did not pass the merging scale criterion.

return -1;

Potentially recluster real emission jets for powheg input containing "too many" jets, i.e. real-emission kinematics.

Remove real emission events without underlying Born configuration from the loop sample, since such states will be taken care of by tree-level samples.

Discard if the state could not be reclustered to any state above TMS.

Check reclustering steps to correctly apply MPI.

Perform one reclustering for real emission kinematics, then apply merging scale cut on underlying Born kinematics.

Initialise temporary output of reclustering.

Recluster once.

Veto if underlying Born kinematics do not pass merging scale cut.

return -1;

Setup to choose shower starting conditions randomly.

Sum up signal and background probabilities.

New UNLOPS strategy based on UN2LOPS.

Calculate weights.

For tree-level or subtractive sammples, rescale with k-Factor

Find k-factor

For NLO merging, rescale CKKW-L weight with k-factor

Calculate CKKWL reweighting for all paths.

Double to access path.

Probability of path.

Calculate CKKWL weight:

Sum up signal and background probabilities separately.

Check if we need to subtract the O()-term. If the number of additional partons is larger than the number of jets for which loop matrix elements are available, do standard UMEPS.

Now begin NLO part for tree-level events

Decide on which order to expand to.

Exclusive inputs: Subtract only the O(^{n+0})-term from the tree-level subtraction, if we're at the highest NLO multiplicity (nMaxNLO).

Exclusive inputs: Do not remove the O(as)-term if the number of reclusterings exceeds the number of NLO jets, or if more clusterings have been performed.

Calculate terms in expansion of the CKKW-L weight.

Exclusive inputs: Subtract the O(^{n+1})-term from the tree-level subtraction, not the O(^{n+0})-terms.

Subtract the O()-term from the CKKW-L weight If PDF contributions have not been included, subtract these later New UNLOPS based on UN2LOPS.

If no-emission probability is zero.

if ( wgt == 0. ) return 0;

Done

bool cutOnProcess ( Event process)
protected

Function to apply the merging scale cut on an input event.

Save number of looping steps

For now, prefer construction of ordered histories.

For pp > h, allow cut on state, so that underlying processes can be clustered to gg > h

Reset any incoming spins for W+-.

Prepare process record for merging. If Pythia has already decayed resonances used to define the hard process, remove resonance decay products.

Store candidates for the splitting V -> qqbar'

Check if event passes the merging scale cut.

Get merging scale in current event.

Calculate number of clustering steps

Too few steps can be possible if a chain of resonance decays has been removed. In this case, reject this event, since it will be handled in lower-multiplicity samples.

Reset the minimal tms value, if necessary.

Potentially recluster real emission jets for powheg input containing "too many" jets, i.e. real-emission kinematics.

Get random number to choose a path.

Set dummy process scale.

Generate all histories

Project histories onto desired branches, e.g. only ordered paths.

Remove real emission events without underlying Born configuration from the loop sample, since such states will be taken care of by tree-level samples.

Cut if no history passes the cut on the lowest-multiplicity state.

Do not apply cut if the configuration could not be projected onto an underlying born configuration.

Now enfore merging scale cut if the event did not pass the merging scale criterion.

Check if more steps should be taken.

Done if no real-emission jets are present.

Now cut on events that contain an additional real-emission jet. Perform one reclustering for real emission kinematics, then apply merging scale cut on underlying Born kinematics.

Initialise temporary output of reclustering.

Recluster once.

Veto if underlying Born kinematics do not pass merging scale cut.

Done if only interested in cross section estimate after cuts.

bool generateHistories ( const Event process,
bool  orderedOnly = true 
)
protected

Function to set up all histories for an event.

Input not valid.

Clear previous history.

For now, prefer construction of ordered histories.

For pp > h, allow cut on state, so that underlying processes can be clustered to gg > h

Prepare process record for merging. If Pythia has already decayed resonances used to define the hard process, remove resonance decay products.

Store candidates for the splitting V -> qqbar'

Calculate number of clustering steps

Set dummy process scale.

Generate all histories

Project histories onto desired branches, e.g. only ordered paths.

Done

bool generateUnorderedPoint ( Event process)
protected

Function to steer different merging prescriptions.

Dryrun to find overestimate enhancements if necessary.

Incoming partons to hard process are stored in slots 3 and 4.

Store participating partons as first set in list of all systems.

Add incoming hard-scattering partons to list in beam remnants.

Scale. Find whether incoming partons are valence or sea. Store.

Done. Clean up event and return.

Generate arbitrary phase-space point with two additional particles.

Incoming partons to hard process are stored in slots 3 and 4.

Store participating partons as first set in list of all systems.

Add incoming hard-scattering partons to list in beam remnants.

Scale. Find whether incoming partons are valence or sea. Store. When an x-dependent matter profile is used with nonDiffractive, trial interactions mean that the valence/sea choice has already been made and should be restored here.

Done. Clean up event and return.

Loop through event and count.

Set number of requested partons.

Loop through event and count.

Set number of requested partons.

double getPathIndex ( bool  useAll = false)
protected

Setup to choose shower starting conditions randomly.

Store a double with which to access each of the paths.

Double to access path.

Randomly pick path.

int getStartingConditions ( double  RNpath,
Event process 
)
protected

Function to perform UNLOPS merging on this event.

Initialise which part of UNLOPS merging is applied.

Save number of looping steps

Calculate number of clustering steps

Potentially recluster real emission jets for powheg input containing "too many" jets, i.e. real-emission kinematics.

Event with production scales set for further (trial) showering and starting conditions for the shower.

Do reclustering (looping) steps.

Set QCD 2->2 starting scale different from arbitrary scale in LHEF! –> Set to minimal mT of partons.

For pure QCD dijet events (only!), set the process scale to the transverse momentum of the outgoing partons.

Reset hard process candidates (changed after clustering a parton).

Check if resonance structure has been changed (e.g. because of clustering W/Z/gluino)

Compare old and new resonances

If necessary, reattach resonance decay products.

Allow merging hooks to remove emissions from now on.

If the resonance structure of the process has changed due to reclustering, redo the resonance decays in Pythia::next()

Done

void init ( )
virtual

Initialisation function for internal use inside Pythia source code.

Initialise Merging class.

Reset minimal tms value.

Reimplemented from Merging.

int mergeProcess ( Event process)
virtual

Functions that implement matrix element merging.

Function to steer different merging prescriptions.

Clear all previous event-by-event information.

Reinitialise hard process.

Remove whitespace from process string

Reset to default merging scale.

Ensure that merging weight is not counted twice.

Directly retrive Sudakov w/o PDF factors from showers and exit. if (doMcAtNloDelta && !usePDF) return genSud(process);

Possibility to apply merging scale to an input event.

Done if only a cut should be applied.

Do not include resonance decay products in the counting.

Loop through event and count.

Set number of requested partons.

Reset to default merging scale.

For ME corrections, only do mergingHooksPtr reinitialization here, and do not perform any veto.

For interative resummed matrix element method, tag histories and exit.

Ensure that merging weight is not counted twice.

Store information before leaving.

Veto if we do not want to do event generation.

Possibility to perform CKKW-L merging on this event.

Possibility to perform UMEPS merging on this event.

Possibility to perform NL3 NLO merging on this event.

Possibility to perform UNLOPS merging on this event.

Reimplemented from Merging.

int mergeProcessCKKWL ( Event process)
protected

Function to perform CKKW-L merging on the event.

Function to perform CKKW-L merging on this event.

Ensure that merging hooks to not veto events in the trial showers.

For pp > h, allow cut on state, so that underlying processes can be clustered to gg > h

Construct all histories. This needs to be done because MECs can depend on unordered paths if these unordered paths are ordered up to some point.

Ensure that merging weight is not counted twice.

Reset weight of the event.

Prepare process record for merging. If Pythia has already decayed resonances used to define the hard process, remove resonance decay products.

Reset any incoming spins for W+-.

Store candidates for the splitting V -> qqbar'.

Check if event passes the merging scale cut. Get merging scale in current event. Calculate number of clustering steps.

Too few steps can be possible if a chain of resonance decays has been removed. In this case, reject this event, since it will be handled in lower-multiplicity samples.

Store hard event cut information, reset veto information.

Reset the minimal tms value, if necessary.

Set dummy process scale.

Generate all histories.

Project histories onto desired branches, e.g. only ordered paths.

Setup to choose shower starting conditions randomly.

Store a double with which to access each of the paths.

Double to access path.

Randomly pick path.

Setup the selected path. Needed for

Do not apply cut if the configuration could not be projected onto an underlying born configuration.

Set event-specific merging scale cut. Q2-dependent for DIS.

Set dynamical merging scale for DIS

Enfore merging scale cut if the event did not pass the merging scale criterion.

Check if more steps should be taken.

Calculate CKKWL reweighting for all paths.

Double to access path.

Probability of path.

Calculate CKKWL weight:

Event with production scales set for further (trial) showering and starting conditions for the shower.

If necessary, reattach resonance decay products.

Allow to dampen histories in which the lowest multiplicity reclustered state does not pass the lowest multiplicity cut of the matrix element.

Save the weight of the event for histogramming. Only change the event weight after trial shower on the matrix element multiplicity event (= in doVetoStep).

Save the weight of the event for histogramming.

Update the event weight.

Allow merging hooks to veto events from now on.

If no-emission probability is zero.

Done

int mergeProcessNL3 ( Event process)
protected

Function to perform NL3 NLO merging on the event.

Function to perform NL3 NLO merging on this event.

Initialise which part of NL3 merging is applied.

Ensure that hooks (NL3 part) to not remove emissions.

Ensure that hooks (CKKWL part) to not veto events in trial showers.

For pp > h, allow cut on state, so that underlying processes can be clustered to gg > h

For now, prefer construction of ordered histories.

Reset weight of the event

Reset the O(alphaS)-term of the CKKW-L weight.

Prepare process record for merging. If Pythia has already decayed resonances used to define the hard process, remove resonance decay products.

Store candidates for the splitting V -> qqbar'

Check if event passes the merging scale cut.

Get merging scale in current event.

Calculate number of clustering steps

Too few steps can be possible if a chain of resonance decays has been removed. In this case, reject this event, since it will be handled in lower-multiplicity samples.

Reset the minimal tms value, if necessary.

Enfore merging scale cut if the event did not pass the merging scale criterion.

Get random number to choose a path.

Set dummy process scale.

Generate all histories

Project histories onto desired branches, e.g. only ordered paths.

Discard states that cannot be projected unto a state with one less jet.

Potentially recluster real emission jets for powheg input containing "too many" jets, i.e. real-emission kinematics.

Perform one reclustering for real emission kinematics, then apply merging scale cut on underlying Born kinematics.

Initialise temporary output of reclustering.

Recluster once.

Veto if underlying Born kinematics do not pass merging scale cut.

Remember number of jets, to include correct MPI no-emission probabilities.

Calculate weight Do LO or first part of NLO tree-level reweighting

Perform reweighting with Sudakov factors, save as ratios and PDF ratio weights

No reweighting, just set event scales properly and incorporate MPI no-emission probabilities.

Event with production scales set for further (trial) showering and starting conditions for the shower

For sutraction of nSteps-additional resolved partons from the nSteps-1 parton phase space, recluster the last parton in nSteps-parton events, and sutract later

Function to return the reclustered event

Allow to dampen histories in which the lowest multiplicity reclustered state does not pass the lowest multiplicity cut of the matrix element

Save the weight of the event for histogramming. Only change the event weight after trial shower on the matrix element multiplicity event (= in doVetoStep)

For tree level samples in NL3, rescale with k-Factor

Find k-factor

For NLO merging, rescale CKKW-L weight with k-factor

Save the weight of the event for histogramming

Check if we need to subtract the O()-term. If the number of additional partons is larger than the number of jets for which loop matrix elements are available, do standard CKKW-L

Now begin NLO part for tree-level events

Calculate the O()-term of the CKKWL weight

If necessary, also dampen the O()-term

Set the subtractive weight to the value calculated so far

Subtract the O()-term from the CKKW-L weight If PDF contributions have not been included, subtract these later

Set qcd 2->2 starting scale different from arbirtrary scale in LHEF! –> Set to pT of partons

For pure QCD dijet events (only!), set the process scale to the transverse momentum of the outgoing partons.

Reset hard process candidates (changed after clustering a parton).

If necessary, reattach resonance decay products.

Allow merging hooks (NL3 part) to remove emissions from now on.

Allow merging hooks (CKKWL part) to veto events from now on.

Done

int mergeProcessUMEPS ( Event process)
protected

Function to perform UMEPS merging on the event.

Function to perform UMEPS merging on this event.

Initialise which part of UMEPS merging is applied.

Save number of looping steps

Ensure that merging hooks does not remove emissions.

For pp > h, allow cut on state, so that underlying processes can be clustered to gg > h

For now, prefer construction of ordered histories.

Ensure that merging weight is not counted twice.

Reset any incoming spins for W+-.

Reset weights of the event.

Prepare process record for merging. If Pythia has already decayed resonances used to define the hard process, remove resonance decay products.

Store candidates for the splitting V -> qqbar'.

Check if event passes the merging scale cut.

Get merging scale in current event.

Calculate number of clustering steps.

Too few steps can be possible if a chain of resonance decays has been removed. In this case, reject this event, since it will be handled in lower-multiplicity samples.

Reset the minimal tms value, if necessary.

Get random number to choose a path.

Set dummy process scale.

Generate all histories.

Project histories onto desired branches, e.g. only ordered paths.

Do not apply cut if the configuration could not be projected onto an underlying born configuration.

Enfore merging scale cut if the event did not pass the merging scale criterion.

Check reclustering steps to correctly apply MPI.

Discard if the state could not be reclustered to a state above TMS.

Calculate CKKWL weight: Perform reweighting with Sudakov factors, save alpha_s ratios and PDF ratio weights.

Event with production scales set for further (trial) showering and starting conditions for the shower.

Do reclustering (looping) steps.

Allow to dampen histories in which the lowest multiplicity reclustered state does not pass the lowest multiplicity cut of the matrix element

Save the weight of the event for histogramming. Only change the event weight after trial shower on the matrix element multiplicity event (= in doVetoStep)

Save the weight of the event for histogramming.

Update the event weight.

Set QCD 2->2 starting scale different from arbitrary scale in LHEF! –> Set to minimal mT of partons.

For pure QCD dijet events (only!), set the process scale to the transverse momentum of the outgoing partons. Calculate number of clustering steps.

Reset hard process candidates (changed after clustering a parton).

If necessary, reattach resonance decay products.

Allow merging hooks to remove emissions from now on.

If no-emission probability is zero.

Done

int mergeProcessUNLOPS ( Event process)
protected

Function to perform UNLOPS merging on the event.

Function to perform UNLOPS merging on this event.

Initialise which part of UNLOPS merging is applied.

Save number of looping steps

Ensure that merging hooks to not remove emissions

For now, prefer construction of ordered histories.

For pp > h, allow cut on state, so that underlying processes can be clustered to gg > h

Reset weight of the event.

Reset the O(alphaS)-term of the UMEPS weight.

Prepare process record for merging. If Pythia has already decayed resonances used to define the hard process, remove resonance decay products.

Store candidates for the splitting V -> qqbar'

Check if event passes the merging scale cut.

Get merging scale in current event.

Calculate number of clustering steps

Too few steps can be possible if a chain of resonance decays has been removed. In this case, reject this event, since it will be handled in lower-multiplicity samples.

Reset the minimal tms value, if necessary.

Get random number to choose a path.

Set dummy process scale.

Generate all histories

Project histories onto desired branches, e.g. only ordered paths.

Do not apply cut if the configuration could not be projected onto an underlying born configuration.

Enfore merging scale cut if the event did not pass the merging scale criterion.

Potentially recluster real emission jets for powheg input containing "too many" jets, i.e. real-emission kinematics.

Remove real emission events without underlying Born configuration from the loop sample, since such states will be taken care of by tree-level samples.

Discard if the state could not be reclustered to any state above TMS.

Check reclustering steps to correctly apply MPI.

Perform one reclustering for real emission kinematics, then apply merging scale cut on underlying Born kinematics.

Initialise temporary output of reclustering.

Recluster once.

Veto if underlying Born kinematics do not pass merging scale cut.

New UNLOPS strategy based on UN2LOPS.

Calculate weights. Do LO or first part of NLO tree-level reweighting

Perform reweighting with Sudakov factors, save as ratios and PDF ratio weights

Set event scales properly, reweight for new UNLOPS

Set event scales properly, reweight for new UNLOPS

Perform reweighting with Sudakov factors, save as ratios and PDF ratio weights

Event with production scales set for further (trial) showering and starting conditions for the shower.

Do reclustering (looping) steps.

Allow to dampen histories in which the lowest multiplicity reclustered state does not pass the lowest multiplicity cut of the matrix element

Save the weight of the event for histogramming. Only change the event weight after trial shower on the matrix element multiplicity event (= in doVetoStep)

For tree-level or subtractive sammples, rescale with k-Factor

Find k-factor

For NLO merging, rescale CKKW-L weight with k-factor

Save the weight of the event for histogramming

Check if we need to subtract the O()-term. If the number of additional partons is larger than the number of jets for which loop matrix elements are available, do standard UMEPS.

Now begin NLO part for tree-level events

Decide on which order to expand to.

Exclusive inputs: Subtract only the O(^{n+0})-term from the tree-level subtraction, if we're at the highest NLO multiplicity (nMaxNLO).

Exclusive inputs: Do not remove the O(as)-term if the number of reclusterings exceeds the number of NLO jets, or if more clusterings have been performed.

Calculate terms in expansion of the CKKW-L weight.

Exclusive inputs: Subtract the O(^{n+1})-term from the tree-level subtraction, not the O(^{n+0})-terms.

If necessary, also dampen the O()-term

Set the subtractive weight to the value calculated so far

Subtract the O()-term from the CKKW-L weight If PDF contributions have not been included, subtract these later New UNLOPS based on UN2LOPS.

Set QCD 2->2 starting scale different from arbitrary scale in LHEF! –> Set to minimal mT of partons.

For pure QCD dijet events (only!), set the process scale to the transverse momentum of the outgoing partons.

Reset hard process candidates (changed after clustering a parton).

Check if resonance structure has been changed (e.g. because of clustering W/Z/gluino)

Compare old and new resonances

If necessary, reattach resonance decay products.

Allow merging hooks to remove emissions from now on.

If no-emission probability is zero.

If the resonance structure of the process has changed due to reclustering, redo the resonance decays in Pythia::next()

Done

void setASratioExp ( vector< double >  wts)
inlineprotected

Clear previous results.

Store coefficients of Sudakov expansion.

void setPDFratiosExp ( vector< double >  wts)
inlineprotected

Clear previous results.

Store coefficients of Sudakov expansion.

void setSudakovExp ( vector< double >  wts)
inlineprotected

Clear previous results.

Store coefficients of Sudakov expansion.

void statistics ( )
virtual

Function to print statistics.

Function to print information.

Recall merging scale value.

Reset minimal tms value.

Header.

Print warning if the minimal tms value of any event was significantly above the desired merging scale value.

Listing finished.

Reimplemented from Merging.

void storeInfos ( )

Clear previous information.

Store information on every possible last clustering.

Just store pT and mass for now.

void tagHistories ( )
protected

Tag history paths as "signal" or "background"

Sum up signal and background probabilities.

Get ME weight.

Reweight with Sudakovs, couplings and PDFs.

Friends And Related Function Documentation

friend class Pythia
friend

The members. Make Pythia class friend


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