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 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?)

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?

Vertexing in root We don’t want to vertex every event. Very time consuming 1 st 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

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.

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)….

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

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?.

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?

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.

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