Search for a new Resonance decaying into Top-Antitop at Tevatron

In this report a new search for a narrow-width heavy resonance decaying into top quark pairs (X → tt) in pp collisions at √s = 1.96 TeV has been performed using data collected by the DØ detector at the Fermilab Tevatron collider. The analysis considers tt candidate events in the lepton+jets channel using a lifetime tag to identify b-jets and the tt invariant mass distribution to search for evidence of resonant production. The analyzed dataset corresponds to an integrated luminosity of approximately 370 pb−1. Since no evidence for a tt resonance X is found, upper limits on σX ×B(X → tt) for different hypothesized resonance masses using a Bayesian approach are set. Within a topcolor-assisted technicolor model, the existence of a leptophobic Z′ boson with MZ′ < 680 GeV and width ΓZ′ = 0.012MZ′ can be excluded at 95% C.L..