Top-mass measurements from D0

We present three recent analyses (Abstracts 169, 170 and 174) of the mass of the top quark (Mt) using top-antitop candidate events collected by the D0 experiment at the Fermilab Tevatron Collider: (i) a 3.6 events/fb sample of data in the lepton+jets channel analyzed to extract a precision value of Mt using the 'Matrix-Element' (ME) method, wherein each event probability is calculated from the differential production cross section as a function of Mt and the overall jet energy scale, with the latter constrained by the two jets from W decay into q(prime)(bar q), (ii) a first measurement of the mass difference between top and antitop quarks as a check of CPT invariance in the quark sector, also based on the ME method in lepton+jets channels, and corresponding to a 1 event/fb data sample, and (iii) measurements of Mt in dilepton final states (updated to 3.6 events/fb), based on 'matrix' weighting, 'neutrino' weighting and the ME method, which rely, respectively, on the likelihood of observing the events in data for a range of assumed Mt values, distributions generated from event weights that compare calculated and reconstructed missing transverse energies, and event probabilities based on the leading-order differential cross section as a function of assumed Mt. In addition, we provide a combination of recent top-mass measurements from D0.