Progress on B-tagging Efficiency Monica Dunford May 22 nd, 2007.
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Progress on B-tagging Efficiency Monica Dunford May 22 nd, 2007
2 Cuts and Jet Selection Two samples: 3mm Pixel and 5mm SCT –Full phi region, incomplete training (referenced as 3x5 sample) –Limited phi 0-90 region (referenced as phi0-90 sample) For all samples, the following are applied –No cuts on truth track association –Track Pt > 1.0GeV, abs( ) < 1.0 –abs(d 0 ) < 2mm and abs(z 0 - z Vertex) < 2.5mm –FTK tracks must have hit in first pixel layer Associate FTK tracks jets using the Cone 0.4 algorithm –Require tracks within < 0.4 and < 0.4 –Jet Pt > 20 GeV and jet abs( )< 0.6 –Must be a b (or u) truth quark within < 0.1 and < 0.1 of jet –Require at least one or more tracks associated with each jet Jets with zero tracks are given a discriminate value of X=0.0
3 Removing Tracks with no First Layer Summary of light quark rejection at B-tagging efficiency of 50% –Have also improve the PDF parameterization since last week –These results are using the 3x5 sample (not fully efficient) FTK signed d0- Last Week FTK signed d0 - no missing 1st layer 20 < Et < 30GeV 30.860.0 30 < Et < 50GeV 19.333.5 50 < Et < 70GeV 34.561.8 70 < Et < 100GeV 27.640.4 Et > 100 GeV 22.333.7 Et > 20 GeV 23.939.3
4 Rejection in a Single phi Region Summary of light quark rejection at B-tagging efficiency of 50% –Using 3x5 sample in different phi regions –The phi cut on the jets within 0.4 radians of the phi region FTK signed d0 (3x5 sample) FTK signed d0 (phi0-90 sample) All regions 39.352.8 (Projected) Phi 0 to 90 58.178.0 Phi 90 to 180 30.1 Phi -180 to -90 38.3 Phi -90 to 0 44.3
5 Summary With a few optimizations of the PDFs, reducing the Jet eta cut and removing FTK tracks with a missing first pixel layer, rejection is 39.3 for jet Et > 20 GeV Using Francesco’s more efficient phi0- 90 banks, rejection for jet Et > 20 GeV is projected at 78.0