Search for resonant production of tt pairs in 4.8 fb-1 of integrated luminosity of pp collisions at √(s)=1.96 TeV

We search for resonant production of tt pairs in 4.8 fb-1 integrated luminosity of pp collision data at √(s)=1.96 TeV in the lepton+jets decay channel, where one top quark decays leptonically and the other hadronically. A matrix-element reconstruction technique is used; for each event a probability density function of the tt candidate invariant mass is sampled. These probability density functions are used to construct a likelihood function, whereby the cross section for resonant tt production is estimated, given a hypothetical resonance mass and width. The data indicate no evidence of resonant production of tt pairs. A benchmark model of leptophobic Z'→tt is excluded with mZ'<900 GeV/c2 at 95% confidence level.