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

TL;DR

This paper reports on searches for rare B meson decays involving invisible particles and sets upper limits on their branching fractions, using data from the Belle detector at KEKB collider.

Contribution

First search for specific B meson decay modes involving invisible particles at Belle, providing upper limits on their branching fractions.

Findings

No significant signals observed for the decay modes.

Upper limits set on branching fractions at 90% confidence level.

Results constrain new physics models predicting such decays.

Abstract

We report results on the search for $B_s\to\eta^{\prime}\eta$ decay, and the searches for $B^0\to\textrm{invisible}$ and $B^0\to\textrm{invisible}+\gamma$ decays. The former result is based on a data sample of $121.4~\textrm{fb}^{-1}$ recorded at the $\Upsilon(5S)$ resonance while the later results are obtained from a $711~\textrm{fb}^{-1}$ of data sample collected at $\Upsilon(4S)$ 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 $\mathcal{B}(B_s\to\eta^{\prime}\eta)<7.1\times 10^{-5}$, $\mathcal{B}(B^0\to\textrm{invisible})<7.8\times 10^{-5}$ and $\mathcal{B}(B^0\to\textrm{invisible}+\gamma)<1.6\times 10^{-5}$.