Observation of the decays B0→K π−π0 and B0→ρ−K

Abstract

We report the observation of B0 decays to the K+π−π0 final state using a data sample of 78 fb−1 collected by the Belle detector at the KEKB e+e− collider. With no assumptions about intermediate states in the decay, the branching fraction is measured to be (36.6−4.3+4.2±3.0)×10−6. We also search for B decays to intermediate two-body states with the same K+π−π0 final state. Significant B signals are observed in the ρ(770)−K+ and K*(892)+π− channels, with branching fractions of (15.1−3.3−1.5−2.1+3.4+1.4+2.0)×10−6 and (14.8−4.4−1.0−0.9+4.6+1.5+2.4)×10−6, respectively. The first error is statistical, the second is systematic and the third is due to the largest possible interference. Contributions..