We report measurements of charmless hadronic B0 decays into the π+π-K+π- final state. The analysis uses a sample of 657×106 BB̄ pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider at the resonance. The decay B0→ρ0K+π- is observed for the first time; the significance is 5.0σ and the corresponding partial branching fraction for MKπ(0.75,1.20)GeV/c2 is [2.8±0.5(stat) ±0.5(syst)]×10-6. We also obtain the first evidence for B0→f0(980)K+π- with 3.5σ significance and for B0→π+π- K0 with 4.5σ significance. For the two-body decays B0→ρ0K0 and B0→f0(980)K*0, the significances are 2.7σ and 2.5σ, respectively, and the upper limits on the branching fractions are 3.4×10-6 and 2.2×10-6 at 90% confidence level. © 2009 The American Physical Society.
Matthias Finger, Qian Wang, Yiming Li, Varun Sharma, Konstantin Androsov, Jan Steggemann, Xin Chen, Rakesh Chawla, Matteo Galli, Jian Wang, João Miguel das Neves Duarte, Tagir Aushev, Matthias Wolf, Yi Zhang, Tian Cheng, Yixing Chen, Werner Lustermann, Andromachi Tsirou, Alexis Kalogeropoulos, Andrea Rizzi, Ioannis Papadopoulos, Paolo Ronchese, Hua Zhang, Siyuan Wang, Tao Huang, David Vannerom, Michele Bianco, Sebastiana Gianì, Sun Hee Kim, Kun Shi, Abhisek Datta, Federica Legger, Gabriele Grosso, Anna Mascellani, Ji Hyun Kim, Donghyun Kim, Zheng Wang, Sanjeev Kumar, Wei Li, Yong Yang, Ajay Kumar, Ashish Sharma, Georgios Anagnostou, Joao Varela, Csaba Hajdu, Muhammad Ahmad, Ioannis Evangelou, Milos Dordevic, Meng Xiao, Sourav Sen, Xiao Wang, Kai Yi, Jing Li, Rajat Gupta, Hui Wang, Seungkyu Ha, Pratyush Das, Anton Petrov, Xin Sun, Valérie Scheurer, Muhammad Ansar Iqbal, Lukas Layer