Search for t(t)over-bar resonances in the lepton plus jets final state in p(p)over-bar collisions at root s=1.96 TeV

We present a search for a narrow-width heavy resonance decaying into top quark pairs (X -> t (t) over bar) in p (p) over bar collisions at root s = 1.96 TeV using approximately 0.9 fb(-1) of data collected with the DO detector at the Fermilab Tevatron Collider. This analysis considers t (t) over bar candidate events in the lepton plus jets channel with at least one identified b jet and uses the t (t) over bar invariant mass distribution to search for evidence of resonant production. We find no evidence for a narrow resonance X decaying to t (t) over bar. Therefore, we set upper limits on sigma x center dot B(X -> t (t) over bar) for different hypothesized resonance masses using a Bayesian approach. For a Topcolor-assisted technicolor model, the existence of a leptophobic Z' boson with mass M(Z') < 700 GeV and width Gamma(Z') = 0.012M(Z') can be excluded at the 95% C.L.