Measurement of Branching Fractions for B->ππ, Kπand KK Decays

Abstract

We report measurements of the branching fractions for $B^0\to {\pi }^{+}{\pi }^{-}$, $K^{+}{\pi }^{-}$, $K^{+}{K}^{-}$ and $K^0{\pi }^0$, and $B^{+}\to {\pi }^{+}{\pi }^0$, $K^{+}{\pi }^0$, $K^0{\pi }^{+}$ and $K^{+}\bar{K}{}^0$. The results are based on 10.4 fb${}^{-1}$ of data collected on the ${\rm Y}$(4S) resonance at the KEKB $e^{+}{e}^{-}$ storage ring with the Belle detector, equipped with a high momentum particle identification system for clear separation of charged $\pi$ and $K$ mesons. We find $\mathcal{B}(B^0\to {\pi }^{+}{\pi }^{-})=(0.56_{-0.20}^{+0.23}\pm 0.04)\times 10^{-5}$, $\mathcal{B}(B^0\to K^{+}{\pi }^{-})=(1.93_{-0.32-0.06}^{+0.34+0.15})\times 10^{-5}$, $\mathcal{B}(B^{+}\to K^{+}{\pi }^0)=(1.63_{-0.33-0.18}^{+0.35+0.16})\times 10^{-5}$, $\mathcal{B}(B^{+}\to K^0{\pi }^{+})=(1.37_{-0.48-0.18}^{+0.57+0.19})\times 10^{-5}$, and $\mathcal{B}(B^0\to K^0{\pi }^0)=(1.60_{-0.59-0.27}^{+0.72+0.25})\times 10^{-5}$, where the first and second errors are statistical and systematic. We also set upper limits of $\mathcal{B}(B^{+}\to {\pi }^{+}{\pi }^0)<1.34\times 10^{-5}$, $\mathcal{B}(B^0\to K^{+}{K}^{-})<0.27\times 10^{-5}$, and $\mathcal{B}(B^{+}\to K^{+}\bar{K}{}^0)<0.50\times 10^{-5}$ at the 90% confidence level.

LaTex, 10 pages, 2 figures, submitted to PRL