RevModPhys.84.1477】Tests of the standard electroweak model at the energy frontier

Events the likelihood methods are described in sec vc

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Unformatted text preview: final state only are shown in Figs. 52 and 53, respectively. The result from combining the results for all low mass final states is shown in Sec. V.C. t t (6.7pb),Single top Diboson NonW Higgs (120 GeV) × 10 Background Uncertainty 3 10 102 (a) DØ W + 2 jet (2 b-tag) L = 1.05 fb -1 Data W + jets multijet tt Wbb other WH x 10 40 10 30 Events Number of events Data W+HF Mistag 1 1515 (115 GeV) 20 10-1 10 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 NN output 0 3 10 (b) 0.2 Data W+HF Mistag (b) DØ L = 1.05 fb -1 30 10 20 Events Number of events 10 0 0.4 0.6 0.8 1 1.2 115 GeV-Neural Network Output t t (6.7pb),Single top Diboson NonW Higgs (120 GeV) × 10 Background Uncertainty 2 -0.2 1 W + 3 jet (2 b-tag) Data W + jets multijet tt Wbb other WH x 10 (115 GeV/c2) 10 10-1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 NN output 1 FIG. 50 (color online). The NN output distributions for (a) single(ST þ NN) and (b) double-tagged (ST þ ST, ST þ JP) events from the CDF 2 fbÀ1 WH search. Rev. Mod. Phys., Vol. 84, No. 4, October–December 2012 0 0 50 100 150 200 250 Dijet Mass (GeV/c2) 300 FIG. 51 (color online). (a) The NN output for double-tagged dijet events and (b) the dijet mass for double-tagged three jet events from the D0 WH search. Hobbs, Neubauer, and Willenbrock: Tests of the standard electroweak model at . . . 1516 3 TABLE XXXIII. Single- and double-tagged yields for the CDF 1:0 fbÀ1 ZH ! ‘‘bb search. Observed Limits for WH 1.9/fb 10 Source 95% CL Limit/SM Expected Limits ± 1σ Z þ bb " Z þ cc Z þ qq " " tt ZZ WZ Non-Z Total expected Observed Signal yield Expected Limits ± 2σ 102 10 1 110 120 130 140 Higgs Mass (GeV/c2) 150 σ (pp → WH) × B(H → bb) (pb) FIG. 52 (color online). The cross-section limits from the CDF WH search. ___ 95% C.L. limits - - - expected limits WH → l ν b b 10 CDF (0.95 fb-1 ) Single tagged 35:1 Æ 14:6 21:8 Æ 8:5 32:3 Æ 5:5 5:2 Æ 1:0 4:0 Æ 0:8 1:2 Æ 0:2 1:9 Æ 1:4 101:5 Æ 32 100 0.44 Double tagged 6:3 Æ 2:5 1:0 Æ 0:4 1:0 Æ 0:2 2:8 Æ 0:6 1:3 Æ 0:3 0:04 Æ 0:01 0:2 Æ 0:2 12:7 Æ 4:1 11 0.23 TABLE XXXIV. Dijet and double-tagged sample yields for the D0 0:45 fbÀ1 ZH ! ‘‘bb search. Source Dijet Double tagged Z þ bb Z þ jj " tt WZ þ ZZ Non-Z Total exp. Observed 17.4 851 12.3 30.6 44.1 956 1008 3.3 3.8 3.9 0.74 0.59 12.3 15 -1 D0 (0.44 fb ) 1 10 -1 100 D0 (1.05 fb-1 ) Standard Model (x4) 110 120 130 140 150 Higgs Mass (GeV/c2) FIG. 53 (color online). The cross-section limits from the D0 WH search. 2. ZH ! ‘‘bb final state The final state from ZH ! ‘‘bb events has the lowest production rate among those shown in Table XXVIII but has the highest purity. A similar strategy is taken for this final state as for the WH final state. An initial sample of Z þ dijet events is selected, the purity is improved by requiring b jets, and the final result is determined by using either the invariant mass distribution or the output of a neural network as inputs to a shape-based limit setting...
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