First Measurement of the B+ -> pi(+)pi(0)pi(0) Branching Fraction and CP Asymmetry

We study B+→π+π0π0 using 711 fb-1 of data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure an inclusive branching fraction of (19.0±1.5±1.4)×10-6 and an inclusive CP asymmetry of (9.2±6.8±0.7)%, where the first uncertainties are statistical and the second are systematic, and a B+→ρ(770)+π0 branching fraction of (11.2±1.1±0.9-1.6+0.8)×10-6, where the third uncertainty is due to possible interference with B+→ρ(1450)+π0. We present the first observation of a structure around 1 GeV/c2 in the π0π0 mass spectrum, with a significance of 6.4σ, and measure a branching fraction to be (6.9±0.9±0.6)×10-6. We also report a measurement of local CP asymmetry in this structure.