CMS-PAS-BTV-15-001

CMS-PAS-BTV-15-001
Identification of b quark jets at the CMS Experiment in the LHC Run 2
CMS Collaboration
March 2016

Abstract: Many physics studies involving standard model processes as well as searches for physics beyond the standard model rely on the accurate identification of jets originating from bottom quarks. The b jet identification algorithms and their performance are presented using proton-proton collision data recorded by the CMS detector at a center of mass energy of $\sqrt{s}=$ 13 TeV during the start of the LHC Run 2 in 2015. The efficiency to identify b quark jets and the probability to misidentify jets originating from non-b quark jets is measured as a function of the jet transverse momentum by selecting events with multiple jets, a Z boson or top quarks. Studies related to the b jet identification efficiency for wide jets with substructure are also presented, relevant for physics analyses targeting b quark jet identification in boosted topologies. Note: For the CSVv2 b jet identification algorithm and for AK4 jets, the achieved relative precision on the scale factors for b quark jets is 1.7% for the loose operating point to 3% for the tight operating point for jets in the pt range between 70 to 100 GeV and it becomes about 4% (loose) to 5% (tight) at the highest considered jet transverse momenta. Overall, the statistical uncertainty is between 15 and 30% of the total uncertainty. The total uncertainty on the scale factor for light quark jets varies between 5% for the loose operating point to 20% for the tight working point for jets in the pt range between 80 to 320 GeV. The total uncertainty is almost fully dominated by systematic effects.
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