16 Integration of Detectors into a Large Experiment: Examples from ATLAS. . .
775
[GeV]
4l
m
100
150
200
250
Events/5 GeV
0
5
10
15
20
25
-1
Ldt = 4.8 fb
∫
s
:
V
e
T
7
=
-1
Ldt = 5.8 fb
∫
s
:
V
e
T
8
=
4l
→
(*)
ZZ
→
H
Data
(*)
Background ZZ
t
Background Z+jets, t
=125 GeV)
H
Signal (m
Syst.Unc.
ATLAS
Fig. 16.35 Distribution of the four-lepton invariant mass for the selected candidates in the H →
ZZ ∗ → 4l channel, as observed by ATLAS at the time of discovery in summer 2012. The expected
signal for m H = 125 GeV is shown stacked on top of the overall background prediction
weights / 2 GeV
Σ
20
40
60
80
100
H γγ
Data S/B Weighted
Sig+Bkg Fit
Bkg (4th order polynomial)
ATLAS
-1
Ldt=4.8fb
∫
=
s
,
V
e
T
7
-1
Ldt=5.9fb
∫
=
s
,
V
e
T
8
=126.5 GeV)
H
(m
[GeV]
γ
γ
m
100
110
120
130
140
150
160
weights - Bkg
Σ
-8
-4
0
4
8
Fig. 16.36 Distribution of the invariant mass of diphoton candidates in the H toγ γ channel,
as observed by ATLAS at the time of discovery in summer 2012. The expected signal for
m H = 125 GeV is shown stacked on top of the overall background prediction. The residuals of the
weighted data with respect to the fitted background is displayed in the bottom panel
that the Higgs couplings to charged third-generation fermions are now all clearly
observed unambiguously and measured to be compatible with SM expectations.
In contrast to the channels used for the discovery, the vast majority of the signals