Search for the Flavor-Changing Neutral-Current Decay t -> Zq in pp Collisions at s=1.96 TeV

We report a search for the flavor-changing neutral-current decay of the top quark t -> Zq (q=u, c) in pp<collisions at s=1.96 TeV using a data sample corresponding to an integrated luminosity of 1.9 fb(-1) collected by the CDF II detector. This decay is strongly suppressed in the standard model and an observation of a signal at the Fermilab Tevatron would be an indication of physics beyond the standard model. Using Z+>= 4 jet final state candidate events, with and without an identified bottom quark jet, we obtain an upper limit of B(t -> Zq)< 3.7% at 95% C.L.