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Plans or JLIP in p17

Plans or JLIP in p17. Benoit Clément, Daniel Bloch, Vincent Siccardi IReS Strasbourg. D Ø Collaboration meeting – B-id meeting September 29th, 2005. Jet axis. Track. q. I.P. Primary vertex. Jet LifeTime Probability (JLIP).

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Plans or JLIP in p17

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  1. Plans or JLIP in p17 Benoit Clément, Daniel Bloch, Vincent Siccardi IReS Strasbourg DØ Collaboration meeting – B-id meeting September 29th, 2005

  2. Jet axis Track q I.P Primary vertex Jet LifeTime Probability (JLIP) Use the signedimpact parameter significance of tracks associated to a jet (dR<0.5 cone matching) to identify jets with long lived particles (mostly b-jets). Impact parameter (IP) sign : - positive for θ < π/2 - negative for θ > π /2

  3. JLIP : Resolution functions Split tracks in 29 categories (considering track pT, η, #SMT hits, #CFT hits and χ2) For each category use negative IP distribution in jet trigger data /Qcd MC to extract resolution functions

  4. JLIP : Track probability For each track : - Determine its category. - Compute track probability. Track probabilities for tracks withpositiveandnegativeIP significance

  5. JLIP : Jet Probability Combine track probabilities for tracks with positive (P+Jet) or negative (P-Jet) significance. P+Jetis the jet probability. Tagging a jet is done by cutting on this value. P-Jetis used to determine mistg rate on QCD data $$

  6. JLIP in p17 No changes in the algorithm. Several improvements were tried on p14 but without any significant result : - Relaxing the track pT cut from 1 to 0.5 GeV. And adding new resolution functions for these tracks. - Adding the Z impact parameter in the probability computation. We do not intend to use these with p17, but might want to redo the studies later on.

  7. JLIP tuning The first task is to recompute… - resolution functions (29 track categories) - impact parameter error correction …on p17 Data and MC and for 2 pass and adaptative PV. We need : - A few millions of QCD data events (QCD and/or EM1TRK) - fixed MC QCD samples (mostly 40-80, 80-160) - time… (~2 weeks once all the samples are available) Note that the MC is critical since NN is trained on MC samples.

  8. Further studies Do we need to produce TRFs and full certification ? Depends mostly on NN schedule : - no need if preliminary NN is ready for Moriond (we can help on the TRFs and systematics) - else, we might be able to produce TRFs with conservative errors by the end of the year. Important studies : - Compare tagger efficiency with 2 pass and adaptative PV. - Look at tagging in MC -> SF close to 1 ?

  9. Summary We plan to continue to maintain JLIP b-tagger for p17, without modification of the algorithm itself. Retuning will be needed before any study can be performed. All the code exist and work with CAF. Have to study PV effect and MC tagging No need of TRFs if NN ready on time. Might be safer to prepare something for JLIP/SVT as well, but schedule already tight.

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