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Analysis of WH(-→jj) Search with D0 Data: Insights on Bump Structures and Phenomenology

This presentation summarizes findings from a September 2010 thesis exploring WH(-→jj) signals using 5.4 fb⁻¹ of D0 data. Key analyses by Shannon Zelitch at the University of Virginia employed the Midpoint algorithm, requiring electron/muon ET > 20 GeV, missing ET > 25 GeV, and jets above specified thresholds using JetClu. The results show both CDF and D0 detect bumps at similar positions, while discrepancies in the DRjj distribution highlight the need for further investigation. Understanding these differences is crucial for refining QCD modeling in search for new physics.

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Analysis of WH(-→jj) Search with D0 Data: Insights on Bump Structures and Phenomenology

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  1. The following slides for D0 were taken from a thesis (Sept 2010) looking for WH(->jj) with 5.4 fb-1 of data • Shannon Zelitch from University of Virginia

  2. Rjet=0.5 Midpoint algorithm

  3. CDF analyses • Require electron/muon ET> 20 GeV and |h|<1.0 • Missing ET > 25 GeV and MTW>30 GeV • Jets using JetClu R=0.4, ET>20 GeV and |h|<2.4 (for WW/WZ search) • increase to 30 GeV (a priori) for bump measurement • Require pTjj>40 GeV/c • The following slides are from Pierliugi’s talk at CERN last week • analysis website: http://www-cdf.fnal.gov/physics/ewk/2011/wjj/

  4. Summary • So both CDF and D0 seem to use ALPGEN+Pythia with mlm matching for calculation of the W/Z+jets background • Both CDF and D0 appear to see bumps at the same place/about the same size • Tilman and Zack not withstanding, the bump does not appear to be caused by tT or single top production • There are residual differences in the DRjj distribution • which are reweighted out by D0 • which are pointed out by CDF as residual systematics, without clear indication of how/whether to correct using sidebands • there is still a bump with the correction, but of a smaller significance • So clearly we need to understand the origin of those residual differences; I believe John Campbell has distributions at NLO, but it would be useful to check with Blackhat+Sherpa, and Sherpa, for the DRjj distribution for W + 2 jets (exclusive), W + 2 jets (inclusive; DRjj between the lead jets), W + 2 jets (inclusive; all DRjj) • This is a major phenomenology weakness, the idea that a major discovery may be either hidden or created by a problem in QCD modelling

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