A Search for tt Resonances in the Dilepton Channel in 2.05 fb−1 of pp collisions at √s = 7 TeV with the ATLAS experiment

A search for a high mass tart resonance in pp collisions at sqrts=7~TeV at the LHC is presented. We search for such a resonance using the final state where the W bosons from the top quark decay into either an electron and electron-neutrino or a muon and muon-neutrino (dilepton final state). The data were recorded by the ATLAS experiment during 2011 and correspond to a total integrated luminosity of calL=2.05 fb−1. No statistically significant excess above the Standard Model expectation is observed. Upper limits at the 95% Confidence Level are set on the cross section times branching ratio of the resonance decaying to ttbar pairs as a function of the resonance mass. A lower mass limit of 1080~GeV is set for the case of a Kaluza-Klein gluon resonance in the Randall-Sundrum Model.