Nonfactorization in B and D decays

Abstract

We discuss the role of nonfactorized contributions in $B \rightarrow ψ+ {K}^{*} $ and charmed meson decays. We demonstrate, using $ {D}^{+}_{S} \rightarrow ϕπ$ as a model, how nonfactorization, annihilation and final state interactions can be built into effective and unitarized $ {a}_{1} $ and $ {a}_{2} $.