Measurement of CP asymmetries and branching fractions in a time-dependent Dalitz analysis of B0→(ρπ)0 and a constraint on the quark mixing angle 2

We present the results of a time-dependent Dalitz plot analysis of B0→π+π-π0 decays based on a 414fb-1 data sample that contains 449×106BB̄ pairs. The data were collected on the Υ(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. Combining our analysis with information on charged B decay modes, we perform a full Dalitz and isospin analysis and obtain a constraint on the quark mixing angle 2, 68°< 2<95° at the 68.3% confidence level for the 2 solution consistent with the standard model. A large standard-model-disfavored region also remains. The branching fractions for the decay processes B0→ρ±(770)π and B0→ρ0(770)π0 are measured to be (22.6±1.1[stat]±4.4[syst])×10-6 and (3.0±0.5[stat] ±0.7[syst])×10-6, respectively. These are the first branching fraction measurements of the process B0→ρ(770)π with the lowest resonance ρ(770) explicitly separated from the radial excitations.