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PWG3 analysis: heavy flavour vertexing

PWG3 analysis: heavy flavour vertexing. Andrea Dainese (INFN Legnaro). AliAnalysisVertexingHF class. single-track cuts on p t and d 0 , (PID...) [common cuts for all analyses]. build all (+,-) pairs and compute secondary vtx. for D + ,D s + , L c +. for D 0  K p , J/ y  ee.

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PWG3 analysis: heavy flavour vertexing

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  1. PWG3 analysis:heavy flavour vertexing Andrea Dainese (INFN Legnaro) ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  2. AliAnalysisVertexingHF class single-track cuts on pt and d0, (PID...) [common cuts for all analyses] build all (+,-) pairs and compute secondary vtx for D+,Ds+,Lc+ for D0Kp, J/yee loop on all tracks (+ & -): build triplets, create AliAODRecoDecayHF3Prong, apply reco cuts (common for the 3 particles?) create AliAODRecoDecayHF2Prong apply reco cuts tight D0 mass cut loop on all tracks for D* candidates for D0Kppp loop on all tracks (+ & -) … create AliAODRecoDecayHF … store D0 store D0 store D*+ store J/y store D+, Ds+, Lc ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  3. AliAnalysisVertexingHF • Input is ESD • Switches and cuts for different analyses (D0, J/y, charm 3 prong, D0 4 prong) • Possibility to have cadidate’s specific primary vertex: • by recomputing from scratch the primary vertex • or by removing the candidate’s daughters from the ESD prim. vertex • Default vertexer is AliVertexerTracks • Added possibility to use Kalman-filter vertexer (AliKFParticle) for secondary vertices • SetSecVtxWithKF() • Current idea for data analysis: • use AliVertexerTracks for first pass on data and production of candidates (loosish reconstruction cuts) • KF vertexer (including constraints) can be used during analysis on candidates, by recomputing the vertex on the fly ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  4. AliAnalysisVertexingHF • AliVertexerTracks::FindCandidatesESDtoAOD(AliESDEvent, TClonesArray*) • Integrated in ANALYSIS framework by AliAnalysisTaskSEVertexingHF • Input:AliESDEvent (single event analysis) • Output: added to existing AliAODEvent • TClonesArray’s with candidates added as branches of a TTree that is attached as friend of aodTree and stored in a separate file AliAOD.VertexingHF.root • Tested in Analysis Train (Mihaela, Silvia) • now run on AliEn by a few users (~5) ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  5. Output in AliAODEvent AliAODEvent • All the I/O managed by AliAODHandler & AliAODInputHandler • Macro to read the candidates: ReadAODVertexingHF.C aodTree in AliAOD.root (standard AOD, unchanged ) friend aodTree in AliAOD.VertexingHF.root vertices (from ESD) AliAODVertex AliAODVertex AliAODVertex ... AliAODTrack AliAODTrack AliAODTrack ... tracks AliAODVertex ... AliAODRecoDecay AliAODRecoDecay ... verticesHF D0toKpi, ... not yet ... ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  6. Candidates analysis from AliAODEvent • AliAnalysisTaskSESelectHF: • read candidates from AliAODEvent (from friend tree) • do some analysis/selection (can also recompute vertex with Kalman filter and use topological/mass constraints) • write candidates to a new branch of the AOD • OR convert candidates to stand-alone and write them to a standard TTree (to be copied on a laptop for making the plots or the invariant mass analysis) TTree D0toKpi AliAODRecoDecay AliAODRecoDecay ... ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  7. Outlook: use the AOD as input • Motivation: AODs are smaller in size, will be replicated in more SEs • Strategy: • AOD well suited for “kinematics” analysis, not for vertexing • ESD well suited for vertexing (AliExternalTrackParam+AliESDVertex) • Use “virtual” interfaces to read ESD or AOD with the same code • in case of AOD input, convert to ExternalTrackParam and ESDVertex • Do vertexing as from ESD ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  8. Development of virtual interfaces (old) Virtual interfaces: AliVEvent AliVParticle ESD world AOD world AliESDEvent AliAODEvent AliESDVertex AliAODVertex AliESDtrack AliAODTrack ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  9. Development of virtual interfaces (new) Virtual interfaces: AliVEvent AliVParticle AliVTrack AliVVertex ESD world AOD world AliESDEvent AliAODEvent AliESDVertex AliAODVertex AliESDtrack AliAODTrack ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  10. Example of analysis code macro: AliESDInputHandler or AliAODInputHandler AliAnalysisTaskSE: AliVVertex *vv = vEvent->GetPrimaryVertex() AliVTrack *vt = vEvent->GetTrack(i) if(!SelectTrack(vt)) continue; // status, ITSClusterMap, ... AliESDtrack esdt(vt); // can now be constructed from XYZPxPyPz parameters (AOD) esdt.PropagateToDCA(vv)  impact parameters AliVertexerTracks vert; AliESDVertex *secv = vert.VertexForSelectedESDTracks(esdtArray) ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  11. Other use-cases • b-jet tagging • impact parameter analysis of tracks from reconstructed jet (has to be run on AOD, where jets are sitting) • Heavy flavour “cascades” (e.g. make a vertex from a D0 and a track  D*+ or B decay) • possible approach: AliAODRecoDecay could derive from AliVTrack and, thus, be used to construct a AliExternalTrackParam that can be used for further vertexing... • AliEVE ? ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  12. Integration of HF into CORRFW • Important missing part in the analysis chain: Acceptance and efficiency (reco & selection) corrections • Plan to use CORRFW • Main HF specific requirement: HF vertices are not in ESD but in AOD • CORRFW currently works on AOD only if there are parallel AOD and Kinematics files • will not be the case with large MC productions (AOD files too many and too small  merge large number of events) • Plan to use AliAODMCParticle info ( Christian) • but... will there be all particles? • Then, adapt to HF vertices • In progress: Renaud, Chiara ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

  13. AOB • Grid/PDCs: • joining request (Ana Marin) of a large pp MB sample (108?) • discussed during next ALICE week • will be useful to run analysis train (incl. HF vertexing) centrally on recent/relevant MC samples  replicas of the resulting AODs in >2 Tiers • Event mixing: • exercise with AliAnalysisTaskME for J/yee • considering necessity to use it for study of HF background... • AliEVE: • visualisation from AOD just started... ALICE Offline Week, CERN, 23.10.08 Andrea Dainese

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