Radiative penguin Bs decays at Belle

We report searches for the radiative penguin decays Bs0 → γ and Bs0 → γγ based on a 23.6 fb-1 data sample collected with the Belle detector at the KEKB e+e− energy-asymmetric collider operating at the γ(5S) resonance. We obtain the first observation of a radiative penguin decay of the Bs0 meson in the Bs0 → γ mode and we measure s(Bs0-+ γ) = (57-15+18 (stat) -17+12 (syst)) × 10-6. No significant Bs0 → γγ signal is observed and we set an upper limit at 90% confidence level of s(Bs0 → γγ) < 8.6 × 10-6. These results are preliminary.