Observation of exclusive Υ(1S) and Υ(2S) decays into light hadrons

Using samples of 102×106 Υ(1S) and 158×106 Υ(2S) events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to the three-body final states Ï•K ⁺K ^-, ωπ ⁺π ^- and K ^*0(892)K ^-π ⁺, and to the two-body Vector-Tensor states (Ï•f2′(1525), ωf ₂(1270), ρa ₂(1320) and K ^*0(892)K̄2*0(1430)) and Axial-vector-Pseudoscalar (K ₁(1270) ⁺K ^-, K ₁(1400) ⁺K ^- and b ₁(1235) ⁺π ^-) states. Signals are observed for the first time in the Υ(1S)→Ï•K ⁺K ^-, ωπ ⁺π ^-, K ^*0K ^-π ⁺, K ^*0K2*0 and Υ(2S)→Ï•K ⁺K ^-, K ^*0K ^-π ⁺ decay modes. Branching fractions are determined for all the processes, while 90% confidence level upper limits are established on the branching fractions for the modes with a statistical significance less than 3σ. The ratios of the branching fractions of Υ(2S) and Υ(1S) decays into the same final state are used to test a perturbative QCD prediction for OZI-suppressed bottomonium decays.