Subleading Isgur-Wise form factors from QCD sum rules

In the heavy-quark effective theory, current matrix elements between two heavy pseudoscalar or vector mesons are parametrized by a set of universal form factors. These functions are calculated to subleading order in the 1mQ expansion using QCD sum rules. The equations of motion and Ward identities of the effective theory are incorporated in the analysis. Within this approach, parameter-free predictions are obtained for all form factors at zero recoil. The results allow for an almost model-independent analysis of current-induced transitions between heavy mesons. As an application, the 1mc and 1mb corrections to the hadronic form factors describing semileptonic B→Dν and B→D*ν decays are computed. The possibility of extracting Vcb from these processes is discussed, and the importance of a measurement of symmetry-violating effects in ratios of form factors is pointed out.