B_s decays at Belle

TL;DR

This paper presents the first measurements of inclusive semileptonic B_s^0 decays, observes the radiative penguin decay B_s^0 -> \phi \\gamma, and sets new limits on B_s^0 \\to \\gamma \\gamma, using data from the Belle detector at the Y(5S) resonance.

Contribution

It reports the first measurement of B_s^0 -> X^+ l^- \\nu decays and the first observation of B_s^0 -> \\phi \\gamma decay, improving understanding of B_s^0 decay modes.

Findings

Branching fraction Bf(B_s^0 -> X^+ l^- \\nu) = (10.2 \\pm 0.8 \\pm 0.9)%

First observation of B_s^0 -> \\phi \\gamma decay

New upper limit set for B_s^0 -> \\gamma \\gamma

Abstract

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^- \nu 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^- \nu) = (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.