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Enhancing EbE Vertexing for LBLB Mixing Analysis: Current Strategies and Future Improvements

This outline presents the current status of EbE vertexing for LBLB mixing analysis, detailing the iterative track selection/pruning algorithm used, understanding of EbE, and plans for enhancements. The text delves into the importance of the hourglass move, EbE integration, and tools like Prompt peak, V-truth, V1-V2, and d0/σ. It also discusses the components involved in Lxy calculations and emphasizes the need for revisiting beamline modeling and secondary vertex resolution. Plans for improvements include understanding beamline parameterization, secondary vertex pulls, using n-prong vertices, and investigating dependencies like Pt, z, and multiplicity. These enhancements aim to achieve significant gains in vertex resolution, control over systematics, and improved EbE accuracy.

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Enhancing EbE Vertexing for LBLB Mixing Analysis: Current Strategies and Future Improvements

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Presentation Transcript

  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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