CERN-THESIS-2012-153 26/07/2012 - CERN Document Server

fake rate [%]
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
40 60 80 100 120 140 160 180 200
(a)
ATLAS
∫
Internal
­1
L dt ~ 100 pb
jet p [GeV]
T
fake rate [%]
0.5
0.45
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
1 2 3 4 5 6 7 8 9 10
(b)
ATLAS
∫
Internal
­1
L dt ~ 100 pb
PV (#tracks ≥ 5)
Figure 6.1: TL fake rate measured from γ+jets events vs. (a) jet pT and (b) number of primary vertices.
The quoted integrated luminosity is a result of the photon trigger prescale.
the matrix of each of the jets. Note that this technique gives the number of fake leptons, not the number of
events with at least one fake lepton.
Figure 6.2: Illustration showing a dilepton + 3 jet event being reconstructed as a trilepton + 2 jet event
with a fake lepton.
Because of the b-tag requirement in the event selection, only events with at least a b-tagged jet contribute
to the fake prediction, and a b-tagged jet only contributes to that prediction if there is another jet in the
event that is b-tagged. This accounts for the fact that if a fake TL emerges from a b-tagged jet, the jet itself
will be removed by the overlap removal and can no longer provide a tag. The 2ID+TL selection requires a
Z-boson candidate, i.e. an opposite-charge, same-flavor, lepton pair. Therefore the parent sample with two
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