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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. R jet =0.5 Midpoint algorithm. CDF analyses. Require electron/muon E T > 20 GeV and | h |<1.0 Missing E T > 25 GeV and M T W >30 GeV
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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
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/
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