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Overview of W+HF Analyses Ford Garberson

Overview of W+HF Analyses Ford Garberson. Introduction/Motivation. Lepton + Jets X-Section with b -Tagging Systematics Table. Many analyses need good understanding of W+heavy -flavor background Many analyses working in different ways Impossible to make one-size-fits all prescription

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Overview of W+HF Analyses Ford Garberson

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  1. Overview of W+HF AnalysesFord Garberson

  2. Introduction/Motivation Lepton + Jets X-Section with b-Tagging Systematics Table • Many analyses need good understanding of W+heavy-flavor background • Many analyses working in different ways • Impossible to make one-size-fits all prescription • But still need to come up with general guidelines • Results are very important for some analyses • Example: top X-section analysis, one of largest systematics!

  3. Approach To Uncertainties • Base results and uncertainties from measurements in low-jet multiplicity bins • Tag-counting analysis (update today) • SV0 mass fit analysis • Now being taken over (with modification) by standard model group • Then project into signal region • 2-jet bin for single top, 3,4,5-jet bin for ttbar • Open questions: • How should we do projection/theory uncertainties • Report on Alpgen studies by Clemens and Daniel today • NLO studies will probably be needed to significantly reduce these uncertainties in the end • Some studies under way in both top and SM groups • How will we cooperate with SM group/use their related results? • Trying to coordinate a meeting with them as soon as possible

  4. Current Prescriptions • Currently assuming: • 1.3 +/- 0.6 for Wbb/Wcc scale factor • To cover significant difference between two measurements • 1.0 +/- 0.4 for Wc scale factor • Driven by measurements before Moriond • Refinements/bug-fixes since then shown on next page. Are these numbers still appropriate?

  5. Latest Measurements Tag-Counting Analysis (Updated numbers today?) Muon Channel SV0 Mass Analysis: (Electron channel not usable) W+b: W+c And cc: Note: subtracting Wcc leads to SF=1.25 in both the 1 and 2-jet bins • Should update our prescriptions? • 1.3 +/- 0.6 still looks ok for Wbb to me for top selection … but some studies in SM group suggest between 2.0-2.5 in 2-jet bin under their selection • But 1.0 +/- 0.4 for Wc does not look so good any more: results are slightly larger now • For SV0 Mass and Tag-Counting Method • Note: SV0 mass has not been updated in some time using top-group selection cuts. SM selection cuts lead to a significantly larger asymmetry between 1-jet and 2-jet bins

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