Search forBs0→hhdecays at theΥ(5S)resonance
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Abstract
We have searched for ${B}_{s}^{0}\ensuremath{\rightarrow}hh$ decays, where $h$ stands for a charged or neutral kaon, or a charged pion. These results are based on a $23.6\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected with the Belle detector on the $\ensuremath{\Upsilon}(5S)$ resonance at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider, containing $1.25\ifmmode\times\else\texttimes\fi{}{10}^{6}$ ${B}_{s}^{(*)}{\overline{B}}_{s}^{(*)}$ events. We observe the decay ${B}_{s}^{0}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$ and measure its branching fraction, $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}})=[{3.8}_{\ensuremath{-}0.9}^{+1.0}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.5(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.5({f}_{s})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. The first error is statistical, the second is systematic, and the third error is due to the uncertainty in the ${B}_{s}^{0}$ production fraction in ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}b\overline{b}$ events. No significant signals are seen in other decay modes, and we set upper limits at the 90% confidence level: $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+})<1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})<2.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, and $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}{K}^{0}{\overline{K}}^{0})<6.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$.