Determination of |V_cb| from exclusive decays in a relativistic quark model

In the framework of a relativistic covariant Bethe-Salpeter model for the quark-antiquark system we present a renewed determination of the Cabibbo-Kobayashi-Maskawa matrix element |V_cb|. Complementing an earlier analysis applied to the whole decay spectrum for B⃗D^*eν we now also employ the “zero-recoil method” that uses the end point of the decay spectrum (ω=1) and is suited for heavy-to-heavy transitions. The averaged experimental value extracted from the data at zero recoil, |V_cb|F(ω=1)=0.0343±0.0015, then leads to |V_cb|=0.0360±0.0016. This value is somewhat larger than the one that uses the whole decay spectrum for the model analysis. We also contrast this result to a nonrelativistic model and to recent experiments on the B⃗Deν semileptonic decay.