Measurements of Charmless Hadronic b->s Penguin Decays in the pi+pi-K+pi- Final State and First Observation of B0 -> rho0K+pi-
Abstract
We report measurements of charmless hadronic B0 decays into the pi+pi-K+pi+ final state. The analysis uses a sample of 657x106 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider at the Y(4S) resonance. The decay B0 -> rho0 Kpi is observed for the first time; the significance is 5.0sigma and the corresponding partial branching fraction for MKpi in (0.75,1.20) GeV/c2 is [2.8 +- 0.5(stat) +-0.5(syst)] x 10-6. We also obtain the first evidence for B0 -> f0Kpi with 3.5sigma significance and for B0 -> pi+pi-K*0 with 4.5sigma significance. For the two-body decays B0 -> rho0K*0 and B0 -> f0K*0, the significances are 2.7sigma and 2.5sigma, respectively, and the upper limits on the branching fractions are 3.4x10-6 and 2.2x10-6 at 90% confidence level.