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

Chapter 6: Event Selection 192
Figure 6.14: Additional smearing needed in simulation using Z → µµ events with
both muons in the barrel (left) and both in the endcap (right). Red lines denote
the fitted width and its statistical uncertainty in data. Black points denote the fitted
width from Monte Carlo.
C1
C2
All events 0.991 ± 0.005 0.055 ± 0.012
BB events 0.992 ± 0.010 0.031 ± 0.020
EE events 0.980 ± 0.012 0.063 ± 0.031
Table 6.12: Scale and extra resolution parameters measured in data by fitting the
Z mass distribution and comparing with Monte Carlo events smeared according to
Eq. 6.11. Errors are statistical only.
Muon momentum scale and resolution from cosmic events
During 2008-2009, ATLAS collected a substantial amount of cosmic muon events.
A fraction of these muons traverse both the muon spectrometer (MS) and the inner
detector (ID). We can derive an estimate of the muon momentum scale and resolution
of the muon spectrometer by comparing the momentum measured in the MS with
that measured in the ID. A detailed study to this effect can be found in [8]. We
summarize below the measurement of muon momentum scale and resolution as a
function of muon pT using matched ID and MS tracks in cosmic events.