Search for $boldsymbol{Bto h ubar{ u}}$ decays with semileptonic tagging at Belle

We present the results of a search for the rare decays $Bto h uoverline{ u}$, 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 $772times10^{6}$ $Boverline{B}$ 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 $Bto K^0_{mathrm{S}} uoverline{ u}$, $B^0to K^{*0} uoverline{ u}$, $Bto pi^+ uoverline{ u}$, $B^0topi^0 uoverline{ u}$, $B^+torho^+ uoverline{ u}$, and $B^0torho^0 uoverline{ u}$ channels are the worlds most stringent.