文摘
We present a measurement of the W-boson polarization in top-quark decays in events with decays to dilepton final states using data corresponding to of integrated luminosity in collisions collected by the CDF II detector at the Tevatron. Assuming a top-quark mass of , a simultaneous measurement of the fractions of longitudinal () and right-handed () W-bosons yields the results and . Combining this measurement with our previous measurement based on single-lepton final states, we obtain and . The results are consistent with the standard model expectation.