Measurement of the branching fraction and CP asymmetry in B0 p0p0 decays, and an improved constraint on ph2
We measure the branching fraction and CP violation asymmetry in the decay B 0 pi(0)pi(0) using a data sample of 752 x 10(6) B (B) over bar pairs collected at the Y(4S) resonance with the Belle detector at the KEKB e()e( collider. The obtained branching fraction and direct CP asymmetry are B(B pi(0)pi(0) [1.31 0.19(stat) 0.19(syst) x 10( 6) and A(CP) +0.14 0.36(stat) 0.10(syst) respectively. The signal significance, including the systematic uncertainty, is 6.4 standard deviations. We combine these results with Belle's earlier measurements of B 0 pi()pi( and B pi( )pi(0) to exclude the CP violating parameter phi(2) from the range 15.5 degrees phi(2) 75.0 degrees at 95% confidence level.