Measurement of Top Branching Ratios at CDF

According to the standard model, the top quark decays to a $W$ boson and a $b$ quark virtually 100\% of the time, and measurements of $t\bar{t}$ production rates depend strongly on that assumption. We test this hypothesis with a measurement of $BR(t \to Wb)/BR(t \to Wq)$, using a combination of event kinematics and b-tagging. We show that the method is independent of the top cross section. We make these comparisons in $t\bar{t}$ samples collected from 340~pb$^{-1}$ of $p\bar{p}$ collision data recorded with the CDF detector at the Tevatron.