LEP measurements of $V_{cb}$ using $B^{0} \to D^{*}^{+}l^{-}\nu$

CKM elements are free parameters to be measured. V/sub cb/ is the main CKM element allowing b decay. Its smallness accounts for the long b lifetime and our ability to observe higher order effects such as B oscillations. V/sub cb/ can be measured from the inclusive semileptonic decay rate of B hadrons to charm states or from the study of the decay rate of B/sup 0/ to D*/sup +/l/sup -/ nu as a function of D*+ recoil kinematics. Inclusive and exclusive channels, a four-velocity product and errors are discussed. (8 refs).CER 1121756 BASE L 13