B_s decays at Belle


Abstract in English

We report recent results obtained with the Belle detector using a 23.6 fb^{-1} data sample collected on the Y(5S) resonance at the KEKB asymmetric energy e^+ e^- collider. Inclusive semileptonic B_s^0 -> X^+ l^- u decays are studied for the first time and the branching fraction is measured. Combining the electron and muon channels, we obtain Bf(B_s^0 -> X^+ l^- u) = (10.2 pm 0.8 pm 0.9)%. Also, the radiative penguin decay B_s^0 -> phi gamma is observed for the first time, and an improved upper limit for the decay B_s^0 to gamma gamma is obtained.

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