Lu, CD (reprint author), CCAST, World Lab, POB 8730, Beijing 100080, Peoples R China.
In this Letter, we investigate the radiative leptonic decays D-(S)(-) --> gammal (υ) over bar (l = e, mu) at tree level within the non-relativistic (s) constituent quark model and the effective Lagrangian for the heavy flavor decays. We find that the contributions from the three Feynman diagrams are all important. With the full calculation, the decay branching ratios are of the order of 10(-5) for D-S(-) --> gammal (υ) over bar (l = e, mu) and 10(-6) for D- --> gammal (υ) over bar (l = e, mu), respectively. These decays can be measured at B factories and future CLEO-C experiments to determine the decay constants fD(s) and f(D). (C) 2003 Published by Elsevier Science B.V.