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

Chapter 9: Discussion and Outlook 240
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Data 2010 ( s = 7 TeV)
Z → µ µ
Fit
ATLAS Preliminary
-1
L dt = 3.37 pb
0
60 70 80 90 100 110 120
[GeV]
∫
mµ
µ
Figure 9.3: Unbinned fit to the Z boson mass peak using a theoretical lineshape
function convolved with a Gaussian function. The Monte Carlo prediction, normalized
to the total number of data events, is also shown.
Carlo.
Fit parameter Value from data [GeV] Value from MC [GeV]
Mean 90.85 ± 0.14 91.30 ± 0.01
Width 2.83 ± 0.17 1.52 ± 0.01
Table 9.3: Mean and width of the Gaussian component of Z lineshape fits. The fit is
made on unbinned data events from a 3.37 pb −1 dataset and on binned Monte Carlo.
Figure 9.4 shows muon kinematic distributions (pT , η and φ) for muons from the
decay of the Z bosons. Figure 9.5 shows the muon pT versus dimuon invariant mass
at two different stages of the Z selection cuts: after the muon pT cut (left) and after
the isolation cut (right) on the decay muons. As with the lower-statistics dataset,