Recent results on hadronic ϒ(1S/2S) decays at Belle

Using the data samples of 102×106ϒ(1S) and 158×106ϒ(2S) events collected at Belle, several studies on ϒ(1S/2S) decays have been performed recently. Charge-parity-even charmonium(-like) states, such as χc0,1,2, ηc, X(3872), X(3915), Y(4140), and X(4350) (only in ϒ(2S) data), are first searched in ϒ(1S/2S) radiative decays, though there are no significant signals observed. Among double-charmonium final states from ϒ(1S/2S) exclusive decays, the evidence for ϒ(1S)→J/ψχc1 was found first with a signal significance of 4.6σ, and the branching fraction was measured to be (3.90 ± 1.21(stat.) ± 0.23(syst.)) × 10-6. Some exclusive light hadronic decays are also searched for the first time, including the intermediate vector-tensor, axial-vector-pseudoscaler, and vector-pseudoscaler processes. Signals are observed in the ϒ(1S)→ϕK+K−, ωπ+π−, K⁎(892)0K−π+, KS0K+π−+c.c., π+π−π0π0, K⁎(892)0K‾2⁎(1430)0 and ϒ(2S)→ϕK+K−, K⁎(892)0K−π+, π+π−π0π0 decay modes, and evidence is found for the modes of ϒ(1S)→π+π−π0, K1(1400)+K−, K⁎(892)0K‾0+c.c. and ϒ(2S)→KS0K+π−+c.c., K⁎(892)0K‾2⁎(1430)0. In addition, the study of the hadronic transitions, ϒ(2S)→(η,π0)ϒ(1S), is performed, and B(ϒ(2S)→ηϒ(1S))=(3.57±0.25(stat.)±0.21(syst.))×106−4 and B(ϒ(2S)→π0ϒ(1S))<4.1×10−5 (90%C.L.) are obtained.