Unformatted text preview: dijet invariant mass for the single- and
double-tagged events in the signal region. The yields are
given in Table XXXVI. The limits on Higgs production are
calculated using the same procedure as for the previous two
channels, and they are shown in Fig. 59.
10 Expected Limit σ(95% CL) (pb) Observed Limit 1
105 FIG. 58 (color online). The dijet invariant mass distributions for
the (a) single-tagged and (b) double-tagged CDF searches in the
VH ! ET bb ﬁnal state.
Rev. Mod. Phys., Vol. 84, No. 4, October–December 2012 110 115 120
Higgs Mass (GeV/c2) 140 145 FIG. 59. Expected and observed 95% C.L. upper bounds on the
VH production cross section for the CDF ET þ bb search.
6 Hobbs, Neubauer, and Willenbrock: Tests of the standard electroweak model at . . . 1519 TABLE XXXVII. The predicted and observed yields for the D0 VH ! ET bb analysis for the untagged control sample and the single- and
double-tagged analysis samples after applying the multijet BDT selection.
Double tagged ZH WH W þ jets Z þ jets Top VV Multijet Total background Observed 13:73 Æ 1:37
4:16 Æ 0:42
4:66 Æ 0:58 11:64 Æ 1:17
3:60 Æ 0:37
4:00 Æ 0:50 19 069
<8 32025 Æ 4037
1830 Æ 255
538 Æ 87 31 718
514 b. D0 search The published D0 analysis uses a data sample correspondR
ing to Ldt ¼ 5:2 fbÀ1 . Events selected for this analysis
must satisfy a trigger requiring two acoplanar jets and ET in
which the kinematic thresholds varied as a function of the
instantaneous luminosity. The primary requirements of the
initial ofﬂine event preselection are at least two jets with
ET > 20 GeV and jj < 2:5, Áðj1 ; j2 Þ < 165 , and ET >
20 GeV. This is divided into four samples: (1) a signal sample
deﬁned by the additional requirements of ET > 40 GeV,
S > 5, D < =2, and a veto of events with high-pT , isolated
leptons; (2) an electroweak test sample enhanced in W !
events and deﬁned similarly as for the signal sample, but
requiring the presence of a high pT , isolated muon; (3) a
multijet modeling sample deﬁned similarly to the signal
sample except D > =2; and (4) a multijet enriched sample
used to conﬁrm the background model predicted using the
multijet modeling sample and deﬁned by ET > 30 GeV and
no requirement on S. Here S is the signiﬁcance of the ET and
D ÁðET ; T T ¼ ET À T T Þ in which T T is the magni6~ 6~
tude of the vector sum of the transverse momentum of the
tracks in the event and i is the azimuthal angle of either
ET or T T .
The presence of b hadrons from the H ! bb signal decay
is used to improve the signal-to-noise ratio. Events were
additionally required to have a least one of the two highest
ET jets identiﬁed as being consistent with a b hadron jet as
determined by a high purity (tight) b-jet identiﬁcation requirement. Events are then categorized as double tagged if the
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