  The first ATLAS result on a search for a high mass top pair resonance at the
LHC, in the subset of events where both W bosons from the top decays decay to
either a final state electron or muon, is presented. The analysis is performed
on 1.04/fb of pp collisions at sqrt(s) = 7 TeV. Numerous models predict the
production of new massive particles that decay preferentially to a top-anti-top
pair, including Randall-Sundrum models where the observation of a Kaluza-Klein
excitation of the gluon may be the first indication of the existence of an
extra spatial dimension. In the analysis presented, a simple observable,
sensitive to resonance mass, is formed by summing the missing transverse
energy, and the transverse momenta of the selected jets and the two candidate
leptons. A deviation from the Standard Model prediction for this observable is
searched for using Bayesian statistical methods that compare the yields, and
shapes, of the Standard Model background and signal predictions for KK-gluons
with masses between 500 and 1600 GeV. No excess over the Standard Model is
observed and 95% C.L. upper limits are set on the production cross-section
times branching ratio to top quarks for KK-gluon-like resonances. The results
of the analysis exclude Randall-Sundrum KK-gluons with masses less than 840
GeV.
