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Processing large data sets

Processing large data sets. Brad Abbott. Now. J/Psi Starting with root-tuples Add 4-momentum to look for candidates Pick events (raw) -> reconstruct event With reco code -> Vertex event if desired Ks V0 block in root-tuple. Now. Okay for near future but time consuming

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Processing large data sets

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  1. Processing large data sets Brad Abbott

  2. Now J/Psi • Starting with root-tuples • Add 4-momentum to look for candidates • Pick events (raw) -> reconstruct event • With reco code -> Vertex event if desired Ks • V0 block in root-tuple

  3. Now • Okay for near future but time consuming • Cross section measurements: Root tuples have enough available information • Many B analyses, we need to take reconstructed info and revertex to find candidates (how do we do this efficiently?)

  4. Vertexing in root • See Suyong’s talk. • Official vertexing in root? • Will we need to go back to reco files to allow us to track with lower Pt cut/ DCA cuts?

  5. Vertexing in root • We don’t want to vertex every event. Very time consuming • 1st pass of stripped data (2 leptons with Pt> n Gev) n to be determined. (Should satisfy many analyses except hadronic decay modes) • Add 4-momentum to see if candidate exists

  6. General root-tuples • Generate B “root-tuples” : standard root-tuples with additional info • What root-tuples do we want?? • J/Psi root-tuple J/Psi, Ks, Phi, K+,K*, etc. • J/Psi cross section, CP violation, B+ lifetime, tagging studies, B->J/Psi, etc.

  7. General root-tuples • Semileptonic root-tuple • Bd->D* l nu Bd mixing • Bs-> Ds l nu Bs mixing • Hadronic root-tuple • Bs-> Ds pi (Ds 3pi)….

  8. Root-tuples • Rare decays ?? (B-> mu mu can add in new decay or increase mass window of J/Psi) • Lambda b ?? • Can these fit easily into the root-tuples Beneficial if few people responsible for generating root-tuple to make sure details correct

  9. Future • Thumbnails. Should be able to vertex directly from thumbnails. Full track error matrix not available. Need to know effects of this on vertexing. • Streaming-> implement special reco? (lower Pt/ different DCA cuts) • Add in new reco analyze code which includes vertexing?.

  10. Vertexing all tracks • Currently V0 in reco which vertexes all tracks. Too time consuming and turned off in MC. • Vertexing Phi, Ds, B is time consuming so will most likely need pre-selection • What pre-selection needed?

  11. Pre-selection • Selecting on trigger enough? • Add 4-momentum to search for candidates? (With low mass objects, almost all events have at least 1 candidate within mass window so very little rejection) • For J/Psi 1st strip feasible, is it possible for semileptonic/hadronic decays.

  12. Efficiently re-vertexing tracks • Need to think about how exactly we want to do this • Feasible if we have intelligent pre-selection of events

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