Top-quark properties at ATLAS with focus on the latest mass and spin correlation measurements

Properties of the top-quark are presented, with emphasis on the most recent ATLAS measurements of the mass and t (t) over bar spin correlations, obtained with proton-proton collision data collected at the Large Hadron Collider. Normalised differential distributions are used in both cases. For the extraction of the top-quark mass, t (t) over bar + 1-jet single-lepton events are selected from the 20.2 fb(-1) 8 TeV dataset, and the unfolded distribution at parton level is compared with theoretical predictions to obtain m(t)(pole) = 171:1(-1.1)(+1.2) GeV in the pole-mass scheme and m(t)(m(t)) = 162:9(-1:6)(+2.4) GeV in the running-mass scheme. For the measurement of spin correlations in t <overline>t production, dilepton events are selected using 36.1 fb(-1) 13 TeV data. The azimuthal opening angle between the two leptons is measured inclusively and as a function of the invariant mass of the t (t) over bar system. The observed degree of spin correlation is significantly higher than predicted by the generators used, but agrees well with the prediction of one of the fixed-order calculations.