Study of $B$ and $B_s$ Decays at Belle

Abstract

We report results on the search for $B_s\to {\eta }^{\prime }\eta$ decay, and the searches for $B^0\to \text{invisible}$ and $B^0\to \text{invisible}+\gamma$ decays. The former result is based on a data sample of $121.4{\text{fb}}^{-1}$ recorded at the ${\rm Y}(5S)$ resonance while the later results are obtained from a $711{\text{fb}}^{-1}$ of data sample collected at ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. We observe no significant signal for the decays and set upper limit on their branching fractions at 90\% confidence level of $\mathcal{B}(B_s\to {\eta }^{\prime }\eta )<7.1\times 10^{-5}$, $\mathcal{B}(B^0\to \text{invisible})<7.8\times 10^{-5}$ and $\mathcal{B}(B^0\to \text{invisible}+\gamma )<1.6\times 10^{-5}$.