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EbE Vertexing for Mixing

EbE Vertexing for Mixing. Alex For the LBL B group. Outline. Current status What was used for the mixing results What is the current understanding of Ebe Plans for improvements How can we improve?. Current status.

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EbE Vertexing for Mixing

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  1. EbE Vertexing for Mixing Alex For the LBLB group

  2. Outline • Current status • What was used for the mixing results • What is the current understanding of Ebe • Plans for improvements • How can we improve?

  3. Current status EbE: itearative track selection/pruning algorithm to provide an unbiased estimate of the PV position on an Event-by-Event basis • Hadronic analyses used a flat ~25um beamline! • Possible improvements: • Move to “hourglass” • Move to EbE • EbE + Hourglass • One of the ½ leptonic analyses used this with fixed hourglass parameters Hourglass

  4. The tools • Prompt peak • V-truth • V1-V2 • d0/ B Lxy d0 

  5. What do we know about EbE? • Unbiased estimator of PVTX Reasonable (~5%) control of systematics

  6. Cross checks using I.P.(B) • Lxy involves three ingredients: • EbE • Secondary vertex • Beamline (in beamline constrained fits) Something funny when beamline is used! Scale factors work! Z dep. Beamline improves pulls! B Lxy d0

  7. B Relative PV/BV contribution to IP and Lxy pulls • Lxy involves three ingredients: • EbE • Secondary vertex • Beamline (in beamline constrained fits) Lxy d0 Beam Constrained Not Beam Constrained PV SV Sum D0 and Lxy probe different regimes of d0/Lxy

  8. …Improvements: • PV pulls w BC  need to revisit modeling of beamline • Difference of relative contributions of PV/SV to Lxy and d0 need additional methods to study SV resolution

  9. Hourglass parameters from DBProfiles

  10. Time dependence of Hourglass parameters Implementing DB access of time-dependent parameters

  11. SV contribution  K • Moments to the rescue: • Example BK • Fit  vertex alone • Look at d0(K) wrt  vertex • Can repeat this study with other multi-prong vertices (D+, D0 etc.). Result might depend on: • Momentum • Vertex multiplicity • Plenty of statistics to study all this d0(K) • Cross check the study on MC, after shimming L00 efficiency

  12. …hence the plans for improvements!A Prioritized List: • Understand beamline parameterization: • Is it modeled correctly • Is it measured correctly  Include our best knowledge of it! • Are secondary vertex pulls ok? • Check with montecarlo truth • Use n-prong vertices (J/K, K+/0, K+/0) • Do we understand the CTVMFT PV scale factor? • (connected to 3.) investigate dependencies (Pt?, z?, multiplicity, ?)

  13. Backup

  14. What do we gain? Euphemism • 15-20% In vertex resolution! • Better control of systematics (hard to evaluate) • Correct EbE resolution (it is not clear that it is correct now) • Red arrow is the effect of 1. Only • Point 2. Affects mostly the green area (tiny ?) • Point 3. Has an effect qualitatively similar to 1., but hard to evaluate

  15. Hadronic analysis systematics ct scale factor 0.000 0.024 0.061 0.090 0.144

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