Precision determination of the CKM element Vcb

We extract the magnitude of the CKM matrix element Vcb and the most relevant parameters of the Heavy Quark Expansion from data of inclusive semileptonic B decays. Our calculation includes the recently computed O(alphas Lambda^2/mb^2) corrections and a careful estimate of the residual theoretical uncertainty. Using a recent determination of the charm quark mass, we obtain |Vcb| = (42.21±0.78)x10-3 and mb_kin(1GeV)=(4.553±0.020)GeV.