A search for t → τνq in ttbar production

We present a search for ttbar events with a tau lepton in the final state. The data sample corresponds to an integrated luminosity of 194 pb^-1 collected with the CDF II detector from ppbar collisions at a center of mass energy of 1.96 TeV. We observe two events with an expected signal of 1.0 ± 0.2 events and a background of 1.3 ± 0.3 events. We determine a 95% confidence level upper limit on r_τ, the ratio of the measured rate of t → τνq to the expectation, of 5.2.