Top Quark Mass Measurements

This note summarizes studies performed in order to estimate the potential of ATLAS to measure the top quark mass from the 1rst few hundred pb^-1 of data. The analyses shown here, based on fully simulated events, have been performed for the channel where the top quarks decay into one lepton plus a number of jets, using various methods to extract the top quark mass. The performance of the detector has been evaluated, including triggering, particle identification, and jet reconstruction. For each method, the expected background, statistical and systematic uncertainties, and linearity have been studied. This work shows that the precision on the top quark mass depends mainly on the jet energy scale uncertainty: a precision of the order of 1 to 3.5 GeV should be achievable with 1 fb^-1, assuming a jet energy scale uncertainty of 1 to 5%