# Search for $\boldsymbol{B\to h\nu\bar{\nu}}$ decays with semileptonic tagging at Belle

## TL;DR

This study searches for rare B meson decays involving neutrinos using semileptonic tagging at Belle, setting the most stringent upper limits to date due to no significant signals observed.

## Contribution

First search for B→hνν̄ decays with semileptonic tagging at Belle, providing the most restrictive upper limits on these branching fractions.

## Key findings

- No significant signals observed in any decay channel.
- Set the world's most stringent upper limits on branching fractions.
- Enhanced sensitivity compared to previous searches.

## Abstract

We present the results of a search for the rare decays $B\to h\nu\overline{\nu}$, where $h$ stands for $K^+,\:K^0_{\mathrm{S}},\:K^{\ast +},\:K^{\ast 0},\:\pi^+,\:\pi^0,\:\rho^+$ and $\rho^{0}$. The results are obtained with $772\times10^{6}$ $B\overline{B}$ pairs collected with the Belle detector at the KEKB $e^+ e^-$ collider. We reconstruct one $B$ meson in a semileptonic decay and require a single $h$ meson but nothing else on the signal side. We observe no significant signal and set upper limits on the branching fractions. The limits set on the $B\to K^0_{\mathrm{S}}\nu\overline{\nu}$, $B^0\to K^{*0}\nu\overline{\nu}$, $B\to \pi^+\nu\overline{\nu}$, $B^0\to\pi^0\nu\overline{\nu}$, $B^+\to\rho^+\nu\overline{\nu}$, and $B^0\to\rho^0\nu\overline{\nu}$ channels are the world's most stringent.