Complete: 1

Disclaimer

Their are large changes planned/done in recent CMSSW releases (>=CMSSW_3_8_4) which are not described in these pages. Once the transition is complete this page will be updated accordingly. Right now the documentation originatates in CMSSW_1_7_X.

RECO/AOD Data Format

CMSSW_3_8_x Expand  CMSSW_3_8_x Collapse 

InputTag/Module (Instance name) Containers Description

tau-tag collections (in RECO and AOD)
missing

CMSSW_1_7_x Expand  CMSSW_1_7_x Collapse 

InputTag/Module (Instance name) Containers Description

tau-tag collections (in RECO and AOD)
coneIsolationTauJetTags reco::IsolatedTauTagInfo (lxr cvs) ConeIsolation dedicated TagInfo. Selected tracks and methods to re-compute the discriminator are present.
coneIsolationTauJetTags reco::JetTag (lxr cvs) Obsolete since 1_6_0.
pfRecoTauTagInfoProducer reco::PFTauTagInfo (lxr cvs) contains treated informations from JetTracksAssociation < a PFJet,a list of Tracks > object which are used for PFTau object elaboration ; in the RECO and AOD content since CMSSW_1_7_0.
pfRecoTauProducer reco::PFTau (lxr cvs) corresponds to the hadronic tau-jet cand. -starting from a PFJet object- that the analysts would use ; in the RECO and AOD content since CMSSW_1_7_0.
pfRecoTauDiscriminationByIsolation reco::PFTauDiscriminatorByIsolation (lxr cvs) associates to each PFTau object the response of a hadr. tau-jet / q/g-jet discrimination procedure based on tracker(+ECAL) isolation ; in the RECO and AOD content since CMSSW_1_7_0.
caloRecoTauTagInfoProducer reco::CaloTauTagInfo (lxr cvs) contains treated informations from JetTracksAssociation < a CaloJet,a list of Tracks > and Island ECAL BasicCluster objects which are used for CaloTau object elaboration ; in the RECO and AOD content since CMSSW_1_7_0.
caloRecoTauProducer reco::CaloTau (lxr cvs) corresponds to the hadronic tau-jet cand. -starting from a CaloJet object- that the analysts would use ; in the RECO and AOD content since CMSSW_1_7_0.
caloRecoTauDiscriminationByIsolation reco::CaloTauDiscriminatorByIsolation (lxr cvs) associates to each CaloTau object the response of a hadr. tau-jet / q/g-jet discrimination procedure based on tracker isolation ; in the RECO and AOD content since CMSSW_1_7_0.

CMSSW_1_6_x Expand  CMSSW_1_6_x Collapse 

InputTag/Module (Instance name) Containers Description

tau-tag collections (in RECO and AOD)
coneIsolationTauJetTags reco::IsolatedTauTagInfo (lxr cvs) ConeIsolation dedicated TagInfo. Selected tracks and methods to re-compute the discriminator are present.
coneIsolationTauJetTags reco::JetTag (lxr cvs) Obsolete since 1_6_0.
combinedTauTag reco::CombinedTauTagInfo (lxr cvs) CombinedTauTag dedicated TagInfo. The Discriminator is computed on a track isolation criteria and a Likelihood computed on the basis of the neutral activity. In the Reco content since 1_6_0.
combinedTauTag reco::JetTag (lxr cvs) Results of the CombinedTauTag Algorithm. In the Reco content since 1_6_0.
pfConeIsolation reco::PFIsolatedTauTagInfo (lxr cvs) Equivalent of the ConeIsolation based tagInfo but made with ParticleFlow objects. The isolation can be computed using charged and neutral particles. In the Reco content since 1_6_0.
tauPFProducer (tauCaloProducer) reco::Tau (lxr cvs) Tau class equivalent to the Muon, Electron and Jet one. Almost all the code for the tagging algorithm is being migrating to use this class as input. In this case the PFConeIsolation is used to fill the relevant variables. In the Reco content since 1_6_0.

Algorithms and Software Architecture

Algorithm for discrimination between hadronic tau-jets and q/g-jets

adrTauJetIsol.png
The main functionality of the CaloTau and PFTau objects is to associate to each corresponding CaloJet / PFJet the response of a following hadronic tau-jet / q/g-jet discrimination procedure based on isolation around a leading (pT>min. value) reco. track / charged hadron PFCandidate (with default values of the parameters in /RecoTauTag/RecoTau/data/CaloRecoTauProducer.cfi, PFRecoTauProducer.cfi files) :
  • step 1 - ask for a leading (pT>5GeV/c) reco. track / charged hadron PFCandidate in a matching cone (DR=0.10) around the jet axis (if not found then return 0 → reco. q/g-jet candidate tagged jet),
  • step 2 - ask for 0/few (0) reco. track(s) / charged hadron PFCandidate(s) in an (DRinnercone=0.10, DRoutercone=0.50) isolation annulus around the leading element (if criterion met then return 1 → reco. tau-jet candidate tagged jet, else return 0),
  • (step 3 - in the case of a PFJet object, may ask for 0/few (0) gamma PFCandidate(s) in an (DRinnercone=0.15, DRoutercone=0.50) isolation annulus around the leading element (if criterion met then return 1 → reco. tau-jet candidate tagged jet, else return 0)).
The above procedure is based on an algorithm introduced in CMS by D. Kotlinski, A. Nikitenko and R. Kinnunen (see CMS Note 2001/017).

A method of discrimination between hadronic tau-jets and electrons

When a CaloTau object is manipulated, the ET of the maximal ET HCAL tower hit inside the initial CaloJet (value accessible through CaloTau::maximumHCALhitEt() public member function) may be used for discrimination between a hadronic tau-jet initiated and an electron initiated CMS.CaloJets.
In CMS NOTE 2006/028 by S. Gennai, F. Moortgat, L. Wendland, A. Nikitenko, S. Wakefield, G. Bagliesi, S. Dutta, A. Kalinowski, M. Konecki and D. Kotlinski two choices of the minimal value -1GeV and 2GeV- of this variable were considered for rejecting electrons faking hadr. tau-jets. For each one, efficiencies of hadr. tau-jet selection and electron selection by the cut were presented.
(When a PFTau object is manipulated, the PFTau::maximumHCALPFClusterEt() public member function returns the ET of the maximal ET HCAL PFCluster inside the PFJet, was created with the will to correspond to the CaloTau::maximumHCALhitEt() member function, was tested only quickly.)

Software Architecture

The code is located in three 3 CMSSW packages :
  • DataFormats/TauReco package, in which are contained the classes defining objects which may be stored for each event and manipulated by an analyst,
    • a 1st layer contains the CaloTauTagInfo and PFTauTagInfo objects in which collected information is used in the elaboration of the 2nd layer objects,
    • a 2nd layer contains the analyst-dedicated CaloTau and PFTau objects -built from the corresponding XXXTauTagInfo objects- in which easily reachable information is relevant for hadronic tau-jet / q/g-jet discrimination, hadronic tau-jet / electron discrimination, hadronic tau-jet Lorentz-vector estimation,
  • RecoTauTag/RecoTau package, in which are contained the EDProducers of the former objects,
  • RecoTauTag/TauTagTools package, in which are contained possibly useful methods.


ALERT! NOTE : in CMSSW_1_6_0 a Tau class (inherited from the RecoCandidate class) appeared. Objects of this class are the hadronic tau-jet candidates that the analyst would manipulate. In CMSSW_1_7_0 and further versions the BaseTau (inherited from the RecoCandidate class), CaloTau and PFTau classes which are the main subjects of the present page will replace the former one.

The CaloTauTagInfo and PFTauTagInfo classes

The EDProducers of these class objects
  • collect informations from JetTracksAssociation < a CaloJet/a PFJet,a list of Tracks > objects collection, and in CaloRecoTauTagInfoProducer from Island ECAL BasicCluster objects collection,
  • filter the rec. Tracks based on their # tracker hits, # pixel hits, χ2, pT…,
    the rec. neutral ECAL BasicClusters, ECAL, HCAL PFClusters based on their E,
  • are configured through /RecoTauTag/RecoTau/data/CaloRecoTauTagInfoProducer.cfi, PFRecoTauTagInfoProducer.cfi files.

OfflineTauIDcodescheme_CMSSW_1_7_0andfurther_1_10oct07.png

The CaloTau and PFTau classes

The EDProducers of these class objects
  • build leading element (a Track or a charged hadr. PFCandidate), lists of signal cone, isolation annulus elements of a hadronic tau-jet cand. possibly using different metrics("DR", "angle", "area " -code mainly due to Christian Veelken) in the definition of the matching cone, signal cone, isolation annulus outer cone sizes.
  • are configured through /RecoTauTag/RecoTau/data/CaloRecoTauProducer.cfi, PFRecoTauProducer.cfi files.

OfflineTauIDcodescheme_CMSSW_1_7_0andfurther_2.png

The CaloTauDiscriminatorByXXX and PFTauDiscriminatorByXXX classes

To each CaloTau (PFTau) object of a collection is associated the response of a discrimination procedure.

The EDProducers of the CaloTauDiscriminatorByIsolation class and the PFTauDiscriminatorByIsolation class objects

  • make use of BaseTau::leadTrack(), ::signalTracks(), ::isolationTrack(), PFTau::leadPFChargedHadrCand(), ::signalPFXXXCands(), ::isolationPFXXXCands functions,
  • for each hadronic tau-jet candidate return the response (0 or 1) of the discrimination by :
    • tracker isolation (asking for no/few rec. Track(s) in an isolation annulus) around a leading rec. Track (return 0 if not found) for a CaloTau,
    • tracker isolation (asking for no/few charged hadron PFCandidate(s) in an isolation annulus) and/or ECAL isolation (asking for no/few gamma PFCandidate(s) in an isolation annulus) around a leading charged hadron PFCandidate (return 0 if not found) for a PFTau,
  • are configured through /RecoTauTag/RecoTau/data/CaloRecoTauDiscriminationByIsolation.cfi, PFRecoTauDiscriminationByIsolation.cfi files.

OfflineTauIDcodescheme_CMSSW_1_7_0andfurther_3.png

-- MatthiasEdelhoff - 11-Nov-2010

Edit | Attach | Watch | Print version | History: r1 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r1 - 2010-11-11 - MatthiasEdelhoff
 
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    CMSPublic All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright & 2008-2019 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback