Nonfactorization in B and D decays

Abstract

We discuss the role of nonfactorized contributions in $B\to \psi +K^{\ast }$ and charmed meson decays. We demonstrate, using $D_S^{+}\to \varphi \pi$ as a model, how nonfactorization, annihilation and final state interactions can be built into effective and unitarized $a_1$ and $a_2$.

10 pages. latex, 3 uuencoded figures appended