Radiative weak annihilation decays - art. no. 033004

A class of meson decay modes sensitive to only one quark topology at leadin g C-F Order (annihilation of valence quarks through a W) is described. No e xperimental observations, or even upper limits, have been reported for thes e decays. This work presents a simpleminded (order-of-magnitude) calculatio n of their branching fractions, and compares to results of previous calcula tions where available. Although rare, one of these modes (D-s(+) --> rho(+) gamma) might already be observable at charm experiments; two others (D+ -- > K*(+) gamma, B+ --> D-s*(+) gamma) should appear at the B factories, and the rest at hadron colliders.