We investigate the radiative dileptonic decays $B_s(B_d)\to\gamma l^+l^-$ within the standard model. Using the constituent quark model, the branching ratios turn out to be around $5\times 10^{ -9}$ for $B_s\to \gamma \mu^+\mu^- $ and around $6\times 10^{ -10}$ for $B_d \to \gamma \mu^+\mu^- $, with slightly larger values for $B_s(B_d) \to \gamma e^+e^- $. The differential rate as a function of the dilepton invariant mass is given. The possibility of using these processes to determine the decay constants of $B_s$ or $B_d$ is discussed.
Categories: hep-ph