Radiative leptonic decays of Ds± and D± mesons

In this Letter, we investigate the radiative leptonic decays D−(s)→γℓν̄ (ℓ=e,μ) at tree level within the non-relativistic 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 Ds−→γℓν̄ (ℓ=e,μ) and 10−6 for D−→γℓν̄ (ℓ=e,μ), respectively. These decays can be measured at B factories and future CLEO-C experiments to determine the decay constants fDs and fD.