B Meson Form Factors and Exclusive Decays

Abstract

We present results for the $B \rightarrow \pi$ and $D\rightarrow \pi$ form factors derived from QCD sum rules on the light-cone. Our predictions are compared with experiment and used to extract the quark mixing parameter $|V_{ub}|$ from a recent CLEO measurement of $B \ra \pi l^+ \nu$. Furthermore, we discuss the factorization approximation for exclusive nonleptonic matrix elements, and describe a first QCD estimate of the nonfactorizable contribution to the amplitude of $B \rightarrow J/\psi K $.