Revisiting B→Dℓν

We re-examine the determination of |Vcb| from B→Dℓν in view of recent experimental and theoretical progress, discussing the parameterization of the form factors and studying the role played by the unitarity constraints. Our fit to experimental and lattice results for B→Dℓν gives |Vcb|=40.49(97) 10−3 and to R(D)=0.299(3).