Measurements of exclusive B_s^0 decays at the Y(5S) resonance

TL;DR

This paper reports measurements of various exclusive B_s^0 decays at the Y(5S) resonance, including branching fractions, production ratios, and meson masses, using data from the Belle detector.

Contribution

First measurement of B_s^0 decay modes and production ratios at the Y(5S) resonance with detailed mass and branching fraction results.

Findings

Significant B_s^0 signal observed in multiple decay modes.

B_s^0 production predominantly via B_s^* ar{B}_s^* pairs.

Measured B_s^0 and B_s^* meson masses with uncertainties.

Abstract

Several exclusive $B_s^0$ decays are studied using a 1.86 fb-1 data sample collected at the Y(5S) resonance with the Belle detector at the KEKB asymmetric energy e^+ e^- collider. In the $B_s^0 \to D_s^- \pi^+$ decay mode we find 10 $B_s^0$ candidates and measure the corresponding branching fraction. Combining the B_s^0 -> D_s^{(*)-} \pi^+, B_s^0 -> D_s^{(*)-} \rho^+, B_s^0 -> J/\psi \phi and B_s^0 -> J/\psi \eta decay modes, a significant $B_s^0$ signal is observed. The ratio \sigma (e^+ e^- -> B_s^* \bar{B}_s^*) / \sigma (e^+ e^- -> B_s^{(*)} \bar{B}_s^{(*)}) = (93^{+7}_{-9} \pm 1)% is obtained at the Y(5S) energy, indicating that $B_s^0$ meson production proceeds predominantly through the creation of $B^*_s \bar{B}^*_s$ pairs. The $B_s^0$ and $B_s^*$ meson masses are measured to be M(B_s^0)=(5370 \pm 1 \pm 3)MeV/c^2 and M(B_s^*)=(5418 \pm 1 \pm 3)MeV/c^2. Upper limits on the B_s^0 -> \gamma \gamma, B_s^0 -> \phi \gamma, B_s^0 -> K^+ K^- and B_s^0 -> D_s^{(*)+} D_s^{(*)-} branching fractions are also reported.