Measurement of angle ϕ2 at the Belle experiment

We present a measurement of the time-dependent CP-violating parameters in B0→π+π− decays with 275 millions pairs and B0→ρ±π± decays with 152 millions pairs collected with the Belle detector at the KEKB asymmetric-energy e+e− collider operating at the ϒ(4S) resonance. We observe large indirect and direct CP asymmetry and using B0→π+π−, we constrain ϕ2 as 0°<ϕ2<19° and 71°<ϕ2<180° at 95.4% C.L. For B0→ρ±π± decay, although CP asymmetry is not significant due to low statistics, ϕ2 is calculated as ϕ2=°(102±13±15).