Muon reconstruction and identification efficiency in ATLAS using the full Run 2 𝒑 𝒑 collision data set at √ 𝒔 = 13 TeV

This article documents the muon reconstruction and identification efficiency obtained by the ATLAS experiment for 139 fb⁻¹ of 𝑝 𝑝 collision data at √𝑠 = 13 TeV collected between 2015 and 2018 during Run 2 of the LHC. The increased instantaneous luminosity delivered by the LHC over this period required a reoptimisation of the criteria for the identification of prompt muons. Improved and newly developed algorithms were deployed to preserve high muon identification efficiency with a low misidentification rate and good momentum resolution. The availability of large samples of 𝑍 → 𝜇𝜇 and 𝐽/𝜓 → 𝜇𝜇 decays, and the minimisation of systematic uncertainties, allows the efficiencies of criteria for muon identification, primary vertex association, and isolation to be measured with an accuracy at the per-mille level in the bulk of the phase space, and up to the percent level in complex kinematic configurations. Excellent performance is achieved over a range of transverse momenta from 3 GeV to several hundred GeV, and across the full muon detector acceptance of |𝜂| < 2.7.