Measurement of the top quark mass in the t ¯t →lepton+jets channel from √ s = 8 TeV ATLAS data and combination with previous results

Abstract

The top quark mass is measured using a template method in the t ¯t → lepton + jets channel (lepton is e or μ) using ATLAS data recorded in 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 20.2 fb−1. The t ¯t → lepton + jets channel is characterized by the presence of a charged lepton, a neutrino and four jets, two of which originate from bottom quarks (b). Exploiting a three-dimensional template technique, the top quark mass is determined together with a global jet energy scale factor and a relative b-to-light-jet energy scale factor. The mass of the top quark is measured to be mtop = 172.08 ± 0.39 (stat) ± 0.82 (syst) GeV. A combinationwith previousATLASmtop measurements gives mtop = 172.69 ± 0.25 (stat) ± 0.41 (syst) GeV.