Search for $B\to h^{(*)}\nu \overline{\nu }$ with the full Belle ${\rm Y}(4S)$ data sample

We report a search for the rare decays $B\to h^{(*)}\nu \overline{\nu }$, where $h^{(*)}$ stands for $K^{+}$, $K_S^0$, $K^{*+}$, $K^{*0}$, ${\pi }^{+}$, ${\pi }^0$, ${\rho }^{+}$, ${\rho }^0$ and $\varphi$. The results are obtained from a $711{\mathrm{fb}}^{-1}$ data sample that contains $772\times {10}^{6}B\overline{B}$ pairs collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. We search for signal candidates by fully reconstructing a hadronic decay of the accompanying $B$ meson and requiring a single $h^{(*)}$ meson left on the signal side. No significant signal is observed and we set upper limits on the branching fractions at 90% confidence level. The measurements of $B^{+}\to K^{*+}\nu \overline{\nu }$, $B^{+}\to {\pi }^{+}\nu \overline{\nu }$, $B^0\to {\pi }^0\nu \overline{\nu }$ and $B^0\to {\rho }^0\nu \overline{\nu }$ provide the world’s currently most restrictive limits.

Figure 1

The quark-level diagrams for the $b\to s\nu \overline{\nu }$ transition in the standard model. (a) Penguin diagram; (b) Box diagram.

Figure 2

The $E_{\mathrm{ECL}}$ distributions for $B\to h^{(*)}\nu \overline{\nu }$ decays. Points with error bars are data; the solid black histogram is the total fit result. The blue cross-hatched region is the background component; the dashed red histogram shows the signal contribution.