Measurement of the top quark mass in the tt¯ → dilepton channel from √s = 8 TeV ATLAS data

Abstract

The top quark mass is measured in the t¯t → dilepton channel (lepton=e, μ) using ATLAS data recorded in the year 2012 at the LHC. The data were taken at a proton–proton centre-of-mass energy of √s = 8 TeV and correspond to an integrated luminosity of about 20.2fb−1. Exploiting the template method, and using the distribution of invariant masses of lepton–b-jetpairs, the top quark mass is measured to be mtop = 172.99 ± 0.41(stat) ± 0.74(syst) GeV, with a total uncertainty of 0.84GeV. Finally, a combination with previous ATLAS mtop measurements from √s = 7 TeV data in the t¯t → dilepton and t¯t → lepton + jets channels results in mtop = 172.84 ±0.34(stat)±0.61(syst) GeV, with a total uncertainty of 0.70GeV.