Measurement of the top quark mass from 2011 ATLAS data using the template method

The top-quark mass (mtop) has been measured using the template method in the channel tt ̄ → lepton+jets (lepton=e, mu) based on ATLAS data recorded in the year 2011. The data were taken at a proton-proton center-of-mass energy of √s = 7 TeV and correspond to an integrated luminosity of about 0.7 fb−1 . The 2-dimensional template analysis determines mtop together with a global jet energy scale factor (JSF). The electron and muon channels yield consistent results. Combining both channels and the results from the 2010 ATLAS data, the top-quark mass is measured with a total uncertainty of 2.8 GeV to be: mtop = (175.9 ± 0.9 stat ± 2.7 syst) GeV.