Search for $B^{-}\to \hat{I}{¼}^{-}\bar{\hat{I}}{½}_{\hat{I}}¼$ Decays at the Belle Experiment

Abstract

We report the result of a search for the decay $B^{-}\to \hat{I}{¼}^{-}\bar{\hat{I}}{½}_{\hat{I}}¼$. The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic $B$-meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of $\mathcal{B}(B^{-}\to \hat{I}{¼}^{-}\bar{\hat{I}}{½}_{\hat{I}}¼)=(6.46\pm 2.22\pm 1.60)\times 10^{-7}$ or a frequentist 90% confidence level interval on the $B^{-}\to \hat{I}{¼}^{-}\bar{\hat{I}}{½}_{\hat{I}}¼$ branching fraction of $[2.9,10.7]\times 10^{-7}$. This result is obtained from a $711{\text{fb}}^{-1}$ data sample that contains $772\times 10^6$ $B\bar{B}$ pairs, collected near the $\hat{I}\yen (4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider.

to be submitted to PRL