We report measurements of the branching fractions and direct CP asymmetries (ACP) 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/B̄0→K±π â̂ mode, we confirm Belle's previously reported large ACP 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 ACP(K +π0)=+0.043±0.024±0.007 with 1.8σ significance. The difference of CP asymmetry between B±→ K±π0 and B0/B̄0→K ±πâ̂ is found to be ΔA Kπ≡ACP(K+π0)-ACP(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 ACP(K+π-)+ACP(K0π+) Γ(K0π+)Γ(K+π-)-A CP(K+π0)2Γ(K+π0)Γ(K +π-)-ACP(K0π0)2Γ(K0π0) Γ(K+π-)=0 and obtain a sum of -0.270±0.132±0.060 with 1.9σ significance.
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|Publication status||Published - 2013 Feb 21|
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)