Measurement of the branching fraction and CP asymmetry in B+ ρ +π0

We report a measurement of the branching fraction for the decay B + → ρ+π0 based on a 140 fb -1 data sample collected with the Belle detector at the KEKB asymmetric e+e- collider. We measure the branching fraction B(B+ →+π0) = (13.2 ± 2.3(stat)-1.9 +(syst)) × 10-6, and the CP-violating asymmetry ACP(B± ρ ±π0) = 0.06 ± 0.17(stat) -0.05 +0.04(syst).© 2005 The American Physical Society.