Measurements of exclusive Bs0 decays at the Υ(5S) resonance
Several exclusive Bs0 decays are studied using a 1.86fb-1 data sample collected at the Υ(5S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. In the Bs0→Ds-π+ decay mode we find 10 Bs0 candidates and measure the corresponding branching fraction. Combining the Bs0→Ds(*)-π+, Bs0→Ds(*)-ρ+, Bs0→J/ψ, and Bs0→J/ψη decay modes, a significant Bs0 signal is observed. The ratio σ(e+e-→Bs*B̄s*)/σ(e+e-→Bs(*) B̄s(*))=(93-9+7±1)% is obtained at the Υ(5S) energy, indicating that Bs0 meson production proceeds predominantly through the creation of Bs*B̄s* pairs. The Bs0 and Bs* meson masses are measured to be M(Bs0)=(5370±1±3)MeV/c2 and M(Bs*)= (5418±1±3)MeV/c2. Upper limits on the Bs0→γγ, Bs0→ γ, Bs0→K+K-, and Bs0→Ds(*)+Ds(*)- branching fractions are also reported. © 2007 The American Physical Society.