Search for $B^0$ Decays to Invisible Final States ($+{\hat{I}}^3$) at Belle

Abstract

We report searches for $B^0\to \mathrm{invisible}$ and $B^0\to \mathrm{invisible}+{\hat{\mathrm{I}}}^3$ decays, where the energy of the photon is required to be larger than 0.5 GeV. These results are obtained from a $711{\mathrm{fb}}^{-1}$ data sample that contains $772\times 10^{6}B\bar{B}$ pairs and was collected near the $\hat{I}\yen (4S)$ resonance with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. We observe no significant signal for either decay and set upper limits on their branching fractions at $90\%$ confidence level of $\mathcal{B}(B^0\to \mathrm{invisible})<7.8\times 10^{-5}$ and $\mathcal{B}(B^0\to \mathrm{invisible}+{\hat{\mathrm{I}}}^3)<1.6\times 10^{-5}$.

submitted to Physical Review D