B-> D* Zero-Recoil Formfactor and the Heavy Quark Expansion in QCD: A Systematic Study

We present a QCD analysis of heavy quark mesons focussing on the B → D* formfactor at zero recoil, F D* (1). An advanced treatment of the perturbative corrections in the Wilsonian approach is presented. We estimate the higher-order power corrections to the OPE sum rule and describe a refined analysis of the nonresonant continuum contribution. In the framework of a model-independent approach, we show that the inelastic contribution in the phenomenological part of the OPE is related to the m Q -dependence of the hyperfine splitting and conclude that the former is large, lowering the prediction for F D* (1) down to about 0.86. This likewise implies an enhanced yield of radial and D-wave charm excitations in semileptonic B decays and alleviates the problem with the inclusive yield of the wide excited states. We also apply the approach to the expectation values of dimension 7 and 8 local operators and to a few other issues in the heavy quark expansion.