7.6.1. Event based analysis¶
Note
The analysis software framework is designed to work with particles. In the default candidate-wise paradigm the analyst takes lists of particles, builds up candidates, loads analysis modules, and saves information (i.e. using the VariablesToNtuple tool) for each candidate. If you are new, it is probably best to start with this approach.
In some situations, it is useful to make cuts on, and write out event-wise information.
Warning
Please note that this use model and the documentation are under development.
Please ask questions at Belle II questions and report bugs using JIRA. Be sure to tag your questions and bug reports as “analysis” and “event based” to help us find them.
VariablesToEventBasedTree¶
The VariablesToNtuple tool writes out one entry in a TTree for every candidate. If you want one entry for every event, you should use the VariableToEventBasedTree module. Note that this still operates on a particle list so you will still need to build up a list of candidates in the normal way.
Here is an example of writing event-wise information for all pions in the event:
import basf2
from stdCharged import stdPi
mypath = basf2.Path()
stdPi('all', path=mypath)
mypath.add_module('VariablesToEventBasedTree',
particleList='pi+:all',
variables=['isSignal', 'mcErrors', 'p', 'E'],
event_variables=['nTracks', 'expNum', 'runNum', 'evtNum'])
- VariablesToEventBasedTree
Calculate variables specified by the user for a given ParticleList and save them into a TTree. The Tree is event-based, meaning that the variables of each candidate for each event are saved in an array of a branch of the Tree.
- Package
analysis
- Library
libVariablesToEventBasedTree.so
- Parameters
- event_variables (list(str), default=[])
List of variables (or collections) to save for each event. Variables are taken from Variable::Manager, and are identical to those available to e.g. ParticleSelector. Only event-based variables are allowed here.
- fileName (str, default=’VariablesToEventBasedTree.root’)
Name of ROOT file for output.
- maxCandidates (unsigned int, default=100)
The maximum number of candidates in the ParticleList per entry of the Tree.
- particleList (str, default=’’)
Name of particle list with reconstructed particles. An empty ParticleList is not supported. Use the VariablesToNtupleModule for this use-case
- sampling (tuple(str, dict(int -> unsigned int)), default=(‘’, {}))
Tuple of variable name and a map of integer values and inverse sampling rate. E.g. (signal, {1: 0, 0:10}) selects all signal events and every 10th background event. Variable must be event-based.
- treeName (str, default=’tree’)
Name of the NTuple in the saved file.
- variables (list(str), default=[])
List of variables (or collections) to save for each candidate. Variables are taken from Variable::Manager, and are identical to those available to e.g. ParticleSelector.
Event based selection¶
Instead of making cuts on properties of particle lists, it is possible to reject all events that fail an event based variable cut. Here is a simple example:
from modularAnalysis import applyEventCuts, buildEventShape
from stdCharged import stdPi
stdPi('all', path=mypath)
buildEventShape(path=mypath)
applyEventCuts('foxWolframR2 < 0.3', path=mypath)
This builds the list of all pions but only processes events where the event-level R2 passes the cut.
See also
B2A307 shows a full example.
- modularAnalysis.applyEventCuts(cut, path)[source]
Removes events that do not pass the
cut(given selection criteria).Example
continuum events (in mc only) with more than 5 tracks
applyEventCuts("[nTracks > 5] and [isContinuumEvent], path=mypath)
Warning
You must use square braces
[and]for conditional statements.- Parameters
cut (str) – Events that do not pass these selection criteria are skipped
path (basf2.Path) – modules are added to this path
Event based variables¶
Here is a list of event based variables on which you can make a cut using the above.
- B0Mode
[Eventbased] It will return the decays mode of B0 particles
- Group
MCParticle tag variables
- Bbar0Mode
[Eventbased] It will return the decays mode of anti-B0 particles
- Group
MCParticle tag variables
- BminusMode
[Eventbased] It will return the decays mode of B- particles
- Group
MCParticle tag variables
- BplusMode
[Eventbased] It will return the decays mode of B+ particles
- Group
MCParticle tag variables
- Bs0Mode
[Eventbased] It will return the decays mode of B_s0 particles
- Group
MCParticle tag variables
- Bsbar0Mode
[Eventbased] It will return the decays mode of anti-B_s0 particles
- Group
MCParticle tag variables
- D0Mode
[Eventbased] It will return the decays mode of D0 particles
- Group
MCParticle tag variables
- Dbar0Mode
[Eventbased] It will return the decays mode of anti-D0 particles
- Group
MCParticle tag variables
- DminusMode
[Eventbased] It will return the decays mode of D- particles
- Group
MCParticle tag variables
- DplusMode
[Eventbased] It will return the decays mode of D+ particles
- Group
MCParticle tag variables
- DsminusMode
[Eventbased] It will return the decays mode of D_s- particles
- Group
MCParticle tag variables
- DsplusMode
[Eventbased] It will return the decays mode of D_s+ particles
- Group
MCParticle tag variables
- DstminusMode
[Eventbased] It will return the decays mode of D*- particles
- Group
MCParticle tag variables
- DstplusMode
[Eventbased] It will return the decays mode of D*+ particles
- Group
MCParticle tag variables
- Ecms
[Eventbased] Returns center-of-mass energy.
- Group
Event
- HighLevelTrigger
[Eventbased] True if event passes the HLT trigger, false if not
- Group
Software Trigger
- IPCov(i, j)
[Eventbased] Returns (i,j)-th element of the covariance matrix of the measured interaction point.
- Group
Event
- IPY
[Eventbased] Returns y coordinate of the measured interaction point.
- Group
Event
- IPZ
[Eventbased] Returns z coordinate of the measured interaction point.
- Group
Event
- L1FTDL(name)
[Eventbased] Returns the FTDL (Final Trigger Decision Logic, before prescale) status of the trigger bit with the given name.
- Group
L1 Trigger
- L1FTDLBit(i)
[Eventbased] Returns the FTDL (Final Trigger Decision Logic, before prescale) status of i-th trigger bit.
- Group
L1 Trigger
- L1Input(name)
[Eventbased] Returns the input bit status of the trigger bit with the given name.
- Group
L1 Trigger
- L1InputBit(i)
[Eventbased] Returns the input bit status of the i-th input trigger bit.
- Group
L1 Trigger
- L1PSNM(name)
[Eventbased] Returns the PSNM (Prescale And Mask, after prescale) status of the trigger bit with the given name.
- Group
L1 Trigger
- L1PSNMBit(i)
[Eventbased] Returns the PSNM (Prescale And Mask, after prescale) status of i-th trigger bit.
- Group
L1 Trigger
- L1PSNMBitPrescale(i)
[Eventbased] Returns the PSNM (prescale and mask) prescale of i-th trigger bit.
- Group
L1 Trigger
- L1Prescale(name)
[Eventbased] Returns the PSNM (prescale and mask) prescale of the trigger bit with the given name.
- Group
L1 Trigger
- L1TimeQuality
[Eventbased] Returns ETimingQuality time quality.
- Group
L1 Trigger
- L1TimeType
[Eventbased] Returns ETimingType time type.
- Group
L1 Trigger
- L1Trigger
[Eventbased] Returns 1 if at least one PSNM L1 trigger bit is true.
- Group
L1 Trigger
- SoftwareTriggerPrescaling(triggerIdentifier)
[Eventbased] return the prescaling for the specific software trigger identifier. Please note, this prescaling is taken from the currently setup database. It only corresponds to the correct HLT prescale if you are using the online database!If the trigger identifier is not found, returns NaN.
- Group
Software Trigger
- SoftwareTriggerResultNonPrescaled(triggerIdentifier)
[Eventbased] [Expert] returns the SoftwareTriggerCutResult, if this trigger would not be prescaled.Please note, this is not the final HLT decision! It is defined as reject (-1), accept (1), or noResult (0). Note that the meanings of these change depending if using trigger or the skim stage, hence expert.If the trigger identifier is not found, returns NaN.
- Group
Software Trigger
- TauminusMode
[Eventbased] It will return the decays mode of tau- particles
- Group
MCParticle tag variables
- TauplusMode
[Eventbased] It will return the decays mode of tau+ particles
- Group
MCParticle tag variables
- beamE
[Eventbased] Returns total beam energy in the laboratory frame.
- Group
Event
- beamPx
[Eventbased] Returns x component of total beam momentum in the laboratory frame.
- Group
Event
- beamPy
[Eventbased] Returns y component of total beam momentum in the laboratory frame.
- Group
Event
- beamPz
[Eventbased] Returns z component of total beam momentum in the laboratory frame.
- Group
Event
- countInList(particleList, cut='')
[Eventbased] Returns number of particle which pass given in cut in the specified particle list. Useful for creating statistics about the number of particles in a list. E.g.
countInList(e+, isSignal == 1)returns the number of correctly reconstructed electrons in the event. The variable is event-based and does not need a valid particle pointer as input.- Group
MetaFunctions
- currentROEIsInList(particleList)
[Eventbased] Returns 1 the associated particle of the current ROE is contained in the given list or its charge-conjugated.Useful to restrict the for_each loop over ROEs to ROEs of a certain ParticleList.
- Group
Rest Of Event
- eventCached(variable)
[Eventbased] Returns value of event-based variable and caches this value in the EventExtraInfo. The result of second call to this variable in the same event will be provided from the cache. It is recommended to use this variable in order to declare custom aliases as event-based. This is necessary if using the eventwise mode of variablesToNtuple).
- Group
MetaFunctions
- eventExtraInfo(name)
[Eventbased] Returns extra info stored under the given name in the event extra info. The extraInfo has to be set first by another module like MVAExpert in event mode. If nothing is set under this name, NaN is returned.
- Group
MetaFunctions
- eventRandom
[Eventbased] Returns a random number between 0 and 1 for this event. Can be used, e.g. for applying an event prescale.
- Group
Miscellaneous
- eventTimeSeconds
[Eventbased] Time of the event in seconds (truncated down) since 1970/1/1 (Unix epoch).
- Group
Event
- evtNum
[Eventbased] Returns the event number.
- Group
Event
- expNum
[Eventbased] Returns the experiment number.
- Group
Event
- genIPY
[Eventbased] Returns y coordinate of the interaction point used for the underlying MC generation. Returns NaN for data.
- Group
Event
- genIPZ
[Eventbased] Returns z coordinate of the interaction point used for the underlying MC generation. Returns NaN for data.
- Group
Event
- generatorEventWeight
[Eventbased] Returns the event weight produced by the event generator
- Group
MC matching and MC truth
- hasRecentInjection
[Eventbased] Returns 1 if an injection happened recently, 0 otherwise.
- Group
Event
- injectionInHER
[Eventbased] Returns 1 if injection was in HER, 0 otherwise.
- Group
Event
- isChargedBEvent
[Eventbased] Returns 1.0 if event contains a charged B-meson on generator level.
- Group
Event
- isContinuumEvent
[Eventbased] Returns 1.0 if event doesn’t contain a \(\Upsilon(4S)\) particle on generator level, 0.0 otherwise.
- Group
Event
- isMC
[Eventbased] Returns 1 if current basf2 process is running over simulated (Monte-Carlo) dataset and 0 in case of real experimental data.
- Group
Event
- isMajorityInRestOfEventFromB0(maskName)
[Eventbased][Expert] Checks if the majority of the tracks in the current RestOfEvent are from a
B0.- Group
Flavor Tagger Expert Variables
- isMajorityInRestOfEventFromB0bar(maskName)
[Eventbased][Expert] Check if the majority of the tracks in the current RestOfEvent are from a
anti-B0.- Group
Flavor Tagger Expert Variables
- isNotContinuumEvent
[Eventbased] Returns 1.0 if event does contain an \(\Upsilon(4S)\) particle on generator level and therefore is not a continuum event, 0.0 otherwise.
- Group
Event
- isPoissonTriggerInInjectionVeto
[Eventbased] Returns 1 if the poisson random trigger is within the injection veto window.
- Group
L1 Trigger
- isUnmixedBEvent
[Eventbased] Returns 1.0 if the event contains opposite flavor neutral B-mesons on generator level, 0.0 in case of same flavor B-mesons and NaN if the event has no generated neutral B.
- Group
Event
- nCleanedECLClusters(cut)
[Eventbased] Returns the number of clean Clusters in the event Clean clusters are defined by the clusters which pass the given cut assuming a photon hypothesis.
- Group
MetaFunctions
- nCleanedTracks(cut)
[Eventbased] Returns the number of clean Tracks in the event Clean tracks are defined by the tracks which pass the given cut assuming a pion hypothesis.
- Group
MetaFunctions
- nKLMClusters
[Eventbased] Returns number of KLM clusters in the event.
- Group
Event
- nMCParticles
[Eventbased] Returns number of MCParticles in the event.
- Group
Event
- nParticlesInList(particleListName)
[Eventbased] Returns number of particles in the given particle List.
- Group
MetaFunctions
- particleRelatedToCurrentROE(var)
[Eventbased] Returns variable applied to the particle which is related to the current RestOfEvent objectOne can use this variable only in a for_each loop over the RestOfEvent StoreArray.
- Group
Rest Of Event
- passesEventCut(cut)
[Eventbased] Returns 1 if event passes the cut otherwise 0. Useful if you want to select events passing a cut without looping into particles, such as for skimming.
- Group
MetaFunctions
- runNum
[Eventbased] Returns the run number.
- Group
Event
- tauMinusMCMode
[Eventbased] Decay ID for the negative tau lepton in a tau pair generated event.
- Group
Generated tau decay information
- tauMinusMCProng
[Eventbased] Prong for the negative tau lepton in a tau pair generated event.
- Group
Generated tau decay information
- tauPlusMCMode
[Eventbased] Decay ID for the positive tau lepton in a tau pair generated event.
- Group
Generated tau decay information
- tauPlusMCProng
[Eventbased] Prong for the positive tau lepton in a tau pair generated event.
- Group
Generated tau decay information
- timeSinceLastInjectionClockTicks
[Eventbased] Time since the last injected bunch passed by the detector in micro seconds.
- Group
Event
- timeSinceLastInjectionMicroSeconds
[Eventbased] Time since the last injected bunch passed by the detector in micro seconds.
- Group
Event
- timeSincePrevTriggerClockTicks
[Eventbased] Time since the previous trigger in clock ticks (127MHz=RF/4 clock).
- Group
Event
- timeSincePrevTriggerMicroSeconds
[Eventbased] Time since the previous trigger in micro seconds.
- Group
Event