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Unformatted text preview: , 2010c) Limit
Limit
Limit
Limit (exp.)
(obs.)
(exp.)
(obs.) 120 130 140 145 150 155 160 165 170 175 180 190 200 9.74
13.6
8.85
12.04 5.40
6.63
4.41
6.38 3.48
5.21
2.85
4.21 3.07
3.94
2.43
3.23 2.58
3.29
2.05
2.62 2.02
3.25
1.67
2.04 1.43
1.82
1.26
1.34 1.36
1.55
1.20
1.29 1.65
1.96
1.44
1.69 2.06
1.89
1.72
1.94 2.59
2.11
2.09
2.24 4.20
3.27
3.24
4.06 6.23
5.53
4.53
6.74 Rev. Mod. Phys., Vol. 84, No. 4, October–December 2012 Hobbs, Neubauer, and Willenbrock: Tests of the standard electroweak model at . . . 1524 Tevatron Run II Preliminary, L=2.05.4 fb 95% CL Limit/SM LEP Exclusion Tevatron
Exclusion Expected
Observed
±1σ Expected
±2σ Expected 10 1 are a factor of 2.7 higher than the SM prediction for mH ¼
115 GeV=c2 and production of a SM Higgs is excluded at the
95% C.L. in the region 163 < mH < 166 GeV=c2 . The results are shown in Fig. 67 expressed as a ratio of the 95% C.L.
upper bound cross section divided by the SM prediction.
VI. SUMMARY AND OUTLOOK 1 SM=1
November 6, 2009 100 110 120 130 140 150 160 170 180 190 200
2 mH(GeV/c ) FIG. 67 (color online). The 95% C.L. upper bounds on the Higgs
production cross section divided by the predicted cross section. This
result includes both published and preliminary results from CDF
and D0. sections of each process (Aaltonen et al., 2009h) (see also
Sec. III.E.4 for the case of SM WW ).
An example NN discriminant distribution for the combination of all categories is shown in Fig. 65, where signal and
background expectations for a 160 GeV=c2 Higgs boson are
compared to the observed data.
No signiﬁcant excess of events beyond SM background
expectations in the NN discriminant are observed. The
95% conﬁdence limits on H , expressed as a ratio to the
expected SM rate as a function of mH , are determined from
the data. The median expected and observed upper limits on
H as a function of mH are shown in Fig. 66.
The expected and observed upper limits at 95% C.L. for
Higgsboson production cross section expressed as a ratio to
the cross section predicted by the SM as a function of mH for
the CDF and D0 searches for H ! WW ðÃÞ in Aaltonen et al.
(2010c) and Abazov et al. (2010b), respectively, are shown in
Table XLI.
C. Combined limits Results for individual search ﬁnal states are combined by
the Tevatron NewPhenomena and Higgs Working Group.
The combinations are updated roughly every six months to
one year using the most up to date preliminary and published
results. The combination is performed using a joint probability density incorporating each channel as an individual result
with systematic uncertainties and their correlations included.
Two algorithms are used for the combination. One is a
Bayesian approach (Aaltonen et al., 2010c), and the other
is a modiﬁed frequentist approach (Junk, 1999; Fisher, 2006).
In both algorithms, the impact of systematic uncertainties is
reduced by treating these as nuisance parameters. Results for
the 95% C.L. upper bound on the Higgs production...
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