Model-independent determinations of B → Dlν, D∗lν form factors Original Research Article

We present non-perturbative, model-independent parametrizations of the individual QCD form factors relevant to B → D∗lν and B → Dlν decays. These results follow from dispersion relations and analyticity, without recourse to heavy quark symmetry. To describe a form factor with two percent accuracy, three parameters are necessary, one of which is its normalization at zero recoil, F(1). We combine the individual form factors using heavy quark symmetry to extract values for the product |Vcb|F(1) from B → D∗lν data with negligible extrapolation uncertainty.