Search for tt Resonances in the Lepton Plus Jets Final State in pp Collisions at √s = 1.96 TeV

Abstract We present a search for a narrow-width heavy resonance decaying into top quarkpairs ( X → t t ¯ ) in p p ¯ collisions at s = 1.96 TeV using approximately 0.9 fb −1 of data collected with the DO detector at the Fermilab TevatronCollider. This analysis considers t t ¯ candidate events in the lepton plus jets channel with at least one identified b jet and uses the t t ¯ invariant massdistribution to search for evidence of resonant production. We find no evidence for a narrow resonance X decaying to t t ¯ . Therefore, we set upper limits on σ X ⋅ B ( X → t t ¯ ) for different hypothesized resonance masses using a Bayesian approach. For a Topcolor-assisted technicolormodel, the existence of a leptophobic Z ′ boson with mass M Z ′ 700 GeV and width Γ Z ′ = 0.012 M Z ′ can be excluded at the 95% C.L.