Search for the Production of Narrow tb-bar Resonances in 1.9 fb-1 of p anti-p Collisions at s**(1/2) =1.96 TeV

We present new limits on resonant tb-bar production in p anti-p collisions at s**(1/2) = 1.96 TeV, using 1.9 fb-1 of data recorded with the CDF II detector at the Fermilab Tevatron. We reconstruct a putative tb-bar mass in events with a lepton, neutrino candidate, and two or three jets, and search for anomalous tb-bar production as modeled by W' --> tb-bar. We set a new limit on a right-handed W' with standard model-like coupling, excluding any mass below 800 GeV/c2 at 95% C.L. For any narrow W'-like state with mass above 800 GeV/c2, the cross-section is found to be less than 0.28 pb at 95% C.L. We also present an exclusion of the W' coupling strength versus W' mass.