PDF《CERN-PH-EP-2011-228》

4 m to

7 m. The πv'

s that decay beyond a radius of ?7 m do not leave hits in the trigger chambers located at ?7 m, while the πv decays that occur before r ?4 m are located in the calorimeter and do not produce suf- ?cient activity in the MS to pass the muon RoI cluster trigger. The mh0 =

120 GeV and mπv =

40 GeV sample has a relatively lower e?ciency because the πv'

s have a lower boost and arrive later at the MS. As a result the trigger signal may be associated with the incorrect bunch crossing, in which case the event is lost. The systematic uncertainty of the muon RoI cluster trigger e?ciency is evaluated on data using a sample of events containing a punch-through jet. This sample of events is similar to signal events as it contains both low energy photons and charged hadrons in a localized region of the MS. These punch-through jets are selected to be in the barrel calorimeter (| η | ≤ 1.4), have ET ≥

20 GeV, at least four tracks in the ID, each with pT ≥

1 GeV and at least

20 GeV of missing transverse momentum aligned with the jet. To ensure signi?cant activity in the MS, the jet is required to contain at least

300 MDT hits in a cone of ?R = 0.6, centered around the jet axis [26]. The muon RoI cluster trigger algorithm was run in the vicinity of the punch-through jet for both data and MC events. The distribution of RoIs contained in the cluster for data and MC events, normalized to the number of data events, is shown in Fig. 2. The shapes of the distribution match r [m]

0 1

2 3

4 5

6 7

8 9

10 Trigger Efficiency

0 0.1 0.2 0.3 0.4 0.5 0.6 =20 GeV v π =120 GeV, m h m =........