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

From both the signal acceptance and the shapes of the

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Unformatted text preview: s couplings. In order to increase the sensitivity to anomalous couplings, these data are combined with the photon ET spectrum from the W analysis (Acosta et al., 2005b) described in Sec. III.E.2 that constrains possible anomalous WW couplings. Table XVII summarizes the resulting anomalous coupling limits under the assumption of equal WW and WWZ couplings. The D0 search for anomalous couplings in the ‘jj channel (Abazov et al., 2009g) is based on the same data that were used to obtain the first evidence for semileptonic decays of WW=WZ boson pairs in hadron collisions (Abazov et al., 2009f). In contrast to the CDF analysis just described, the D0 analysis uses the dijet pT information Hobbs, Neubauer, and Willenbrock: Tests of the standard electroweak model at . . . (a) EPD < 0.25 1501 (b) 0.25 < EPD < 0.5 600 Events / 6 GeV/c2 Events / 6 GeV/c2 150 400 200 50 30 (c) 0.5 < EPD < 0.75 Events / 6 GeV/c2 60 Events / 6 GeV/c2 100 40 20 (d) 0.75 < EPD Data (2.7 fb-1) 25 WW+WZ 20 W/Z+jets 15 QCD 10 Top 5 0 50 100 150 0 200 50 2 100 150 200 Mjj (GeV/c2 ) Mjj (GeV/c ) FIG. 35 (color online). For the CDF analysis, Mjj for events with (a) EPD < 0:25, (b) 0:25 < EPD < 0:5, (c) 0:5 < EPD < 0:75, and (d) EPD > 0:75. From Aaltonen et al., 2010b. 8. VV (V ¼ W , Z) Data Events/350 pb-1 102 λ= ∆κ=0.5, Λ=1.5 TeV SM expectation 10 1 10-1 10-2 0 100 20 30 400 500 pW (GeV/c) T FIG. 36 (color online). The pW distribution used for setting the T anomalous TGC limits in the CDF analysis. Shown are the SM expectation, data points, and one anomalous coupling scenario with  ¼ Á ¼ 0:5 and à ¼ 1:5 TeV. From Aaltonen et al., 2007a. to place limits on WW =Z anomalous couplings. Figure 37 shows the dijet pT distribution after a fit for the individual signal and background contributions. No excess at high dijet pT that would suggest that nonstandard couplings are present is evident in the data. The one-dimensional 95% C.L. limits for the WW =Z anomalous coupling parameters under separate assumptions of SUð2ÞL  Uð1ÞY symmetry and equal WW and WWZ couplings are shown in Table XVIII. The 2D limits under the assumption of SUð2ÞL  Uð1ÞY symmetry (Hagiwara et al., 1993) are shown in Fig. 38 and for equal coupling assumption they are shown in Fig. 39. Rev. Mod. Phys., Vol. 84, No. 4, October–December 2012 In Secs. III.E.4, III.E.5, and III.E.6, we summarized the observations of heavy vector boson pairs (WW , WZ, ZZ) when each boson decays to one or more charged leptons. In Sec. III.E.7, the measurements of a hadronically decaying heavy vector boson produced in association with a W boson that decays to a charged lepton and a neutrino were described. Observing diboson production in semileptonic decay mode required sophisticated analysis techniques because of overwhelming W þ jets in addition to the presence of a WW þ WZ signal. The approach of searching for diboson production in a more inclusive way can be taken a step further by...
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