Rare B Decays at Belle

Abstract

Recent results of rare B decay analyses based on 31.9 million $B\bar{B}$ collected with the Belle detector at the KEKB asymmetric $e^+e^-$ collider are presented. We have made the first observation of charmless baryonic decay $B^\pm \to p \bar{p} K^\pm$, the three-body $B^0 \to K^0 \pi^+ \pi^-$ and $B^0 \to K^0 K^+ K^-$. The measured branching fractions are $\mathcal{B}(B^+\to p \bar{p} K^+) = (4.3^{+1.1}_{-0.9} \pm 0.5)\times 10^{-6}$, $\mathcal{B}(B^0{\to}K^0\pi^+\pi^-) = (\brkspp) \times 10^{-6}$, and ${\mathcal{B}}(B^0{\to}K^0 K^+ K^-) = (\brkskk) \times 10^{-6}$. We also see strong evidence of $B^\pm \to \eta K^\pm$ and $B^\pm \to \eta \pi^\pm$, and observed the decay $B^\pm \to \omega K^\pm$ with $\mathcal{B}(B^\pm \to \omega K^\pm) = (9.9^{+2.7}_{-2.4} \pm 1.0) \times 10^{-6}$. Preliminary results of improved measurements of the branching fractions for the decays $B \to K \pi$ and $\pi \pi$ are reported. No evidence for direct CP violation is found in the decays $B^\pm \to K^\pm \pi^\mp$, $K^\pm \pi^0$, $K^0 \pi^\pm$, $\pi^\pm \pi^0$, and $\omega K^\pm$.