Difference: WorkBookMuonAnalysis (88 vs. 89)

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7.8 Muon Analysis

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 The tracker-muon algorithm is particularly useful for the identification of low-pT muons (with pT of the order of several GeV), which may not leave enough hits in the muon stations for a standalone muon to be reconstructed. The default criteria for tagging a tracker track as "tracker muon" are very loose (in CMSSW_3_X_Y series, every track with p > 2.5 GeV and pT > 0.5 GeV matched with at least one segment in the muon stations is labeled as "tracker muon"), so tracker muons should in general not be used without further requirements. Several sets of such requirements recommended by the muon POG are described in Sections 6-8 of CMS AN 2008/098; the corresponding flags can be retrieved from the reco::Muon object (see WorkBook section on muon ID).

RPC muons

An approach similar to Tracker Muons is followed to define the RPC Muons: in this case a match is sought between the extrapolated inner track and hits on the RPC muon detectors. A description of the algorithm and the performance measurements is contained in the CMS AN-2012/482 . The effects of including the RPC hits in the global muon reconstruction have also been studied and are described in M.S.Kim, JINST 8 (2013) T03001 . The main twiki page documenting the RPC Muon algorithm is linked HERE .

Calorimeter-based muons

Calorimeter-based muons, or "calo muons" for short, represent a subset of all tracker tracks reconstructed in the event, which includes tracks with energy depositions in the calorimeters compatible with those of a minimum-ionizing particle. The fake rate of these muon candidates is high and they should not be used when muon purity is essential. A typical use case for "calo muons" is the reconstruction of the J/ψ decaying to low-momentum muons that have little or no information in the muon system, thus improving signal to background ratio compared with the inner tracks. In the event record, "calo muons" are stored in a collection of dedicated objects, reco::CaloMuon's.
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