CP violation measurements in B mesons at Belle

We present recent measurements of time-dependent CP asymmetries in two neutral B decay modes: B0 → η'K0 and B0 → ωK°S. The measured values of mixing-induced (sin 21eff) and direct CP violation parameters are: Sη'Ko = +0.68 ± 0.07stat ± 0.03syst, Aη'K0 = +0.03 ± 0.05stat ± 0.04syst and SωK0S = +0.91 ± 0.32stat ± 0.05syst, AωK0S = -0.36 ± 0.19stat ± 0.05syst, respectively. These results are fully consistent with the current world average of sin 21 measured in b → cs transitions, and represent the most accurate measurements in these modes up-to- date. In addition, we present a new preliminary update on branching ratio measurement in B0 → π0π0 decay mode, the result of which: (B0 → π0π0) = (0.90 ± 0.12stat ± 0.10syst) × 10−6 represents an important ingredient in a ππSU(2) isospin analysis, used to experimentally extract 2 angle from B → ππ measurements. To obtain CP violation parameters ((B0 → π0π0)) the final data set of 772 × 106 (751.5 × 106) B pairs collected at the (4S) resonance with the Belle detector at the KEKB asymmetric e+e− collider in Japan (3.5 × 8.0GeV) is used.