QCD Aspects of Exclusive B Decays

Exclusive B decays can be factorized as convolutions of hard scattering amplitudes involving the weak interaction with universal hadron distribution amplitudes, thus providing a new QCD-based phenomenology. In addition, semi-leptonic decay amplitudes can be computed exactly in terms of the diagonal and off-diagonal overlap of hadronic light-cone wavefunctions. I review these formalisms and the essential QCD ingredients. canonical form of the light-cone wavefunctions, valid at low values of the transverse momenta, is presented. The existence of intrinsic charm Fock states in the B meson wavefunction can enhance the production of final states of B -decay with three charmed quarks, such as B --> J/psi D pi, as well as lead to the breakdown of the CKM hierarchy.