## Abstract

We report measurements of the branching fractions and direct CP asymmetries (A_{CP}) for B→Kπ, ππ and KK decays (but not π0π0) based on the final data sample of 772×106 BB̄ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider. We set a 90% confidence-level upper limit for K^{+}K^{-} at 2.0×10^{-}7; all other decays are observed with branching fractions ranging from 10^{-}6 to 10 ^{-}5. In the B0/B^{̄}0→K^{±}π ^{â̂} mode, we confirm Belle's previously reported large A_{CP} with a value of -0.069±0.014±0.007 and a significance of 4.4σ. For all other flavor-specific modes, we find A _{CP} values consistent with zero, including A_{CP}(K ^{+}π0)=+0.043±0.024±0.007 with 1.8σ significance. The difference of CP asymmetry between B^{±}→ K^{±}π0 and B0/B^{̄}0→K ^{±}π^{â̂} is found to be ΔA _{Kπ}≡A_{CP}(K^{+}π0)-A_{CP}(K ^{+}π^{-})=+0.112±0.027±0.007 with 4.0σ significance. We also calculate the ratios of partial widths for the B→Kπ decays. Using our results, we test the validity of the sum rule A_{CP}(K^{+}π^{-})+A_{CP}(K0π^{+}) Γ(K0π^{+})Γ(K^{+}π^{-})-A _{CP}(K^{+}π0)2Γ(K^{+}π0)Γ(K ^{+}π^{-})-A_{CP}(K0π0)2Γ(K0π0) Γ(K^{+}π^{-})=0 and obtain a sum of -0.270±0.132±0.060 with 1.9σ significance.

Original language | English |
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Article number | 031103 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 87 |

Issue number | 3 |

DOIs | |

Publication status | Published - 2013 Feb 21 |