Measurement of the Z boson cross-section in - Harvard University ...

Chapter 6: Event Selection 168
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dt = 331 nb
Data 2010 ( s=7
TeV)
Z → µ µ
bb cc
W → µ ν
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Z →
tt
τ
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RPC eta hits/track
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Data 2010 (
Z → µ µ
bb
cc
W → µ ν
Z → τ
tt
s=7
TeV)
0 2 4 6 8 10 12 14 16
RPC phi hits/track
Figure 6.3: RPC η (left) and φ (right) hits per muon track for signal Monte Carlo,
background Monte Carlo and data after event preselection. The total Monte Carlo
event number has been normalized to the number of events in data.
disagreement is expected. In addition, the amount of cross-talk is expected to be
worse in φ than in η [59], which is what we observe.
We note that the 0-hit bin is due to tracks in the barrel which, of course, do not
traverse the TGCs.
Figure 6.5 shows the number of Pixel hits on the inner detector track associated
with the combined muon track. Most tracks have at least 3 Pixel hits, as expected
(Section 2.2.2). Tracks that traverse overlap regions between Pixel layers have more
than 3 hits. In all bins, we see good agreement between data and Monte Carlo.
Figure 6.6 shows the number of SCT and TRT hits on the track. The SCT
hit plot shows the sum of hits on the axial/radial sides and the stereo sides of the
strips. Consequently, at least 8 hits are expected on a typical track from the 4 SCT
layers. Smaller hit multiplicities result from hit association inefficiencies in the SCT.