Measurement of exclusive Upsilon(1S) and Upsilon(2S) decays into vector-pseudoscalar final states

Abstract

Using samples of 102 million Upsilon(1S) and 158 million Upsilon(2S) events collected with the Belle detector, we study exclusive hadronic decays of these two bottomonium resonances to (KSK+)-K-0 pi(-) and charge-conjugate (c.c.) states, pi(+) pi(-) pi(0) pi(0), and pi(+) pi(-) pi(0), and to the two-body Vector-Pseudoscalar (K*(892)0 (K) over bar (0) + c.c., K*(892)K--(+) + c.c., omega pi(0), and rho pi) final states. For the first time, signals are observed in the modes Upsilon(1S) -> K-S(0) K+ pi(-) + c.c., pi(+) pi(-) pi(0) pi(0), and Upsilon(2S) -> pi(+) pi(-) pi(0) pi(0), and evidence is found for the modes Upsilon(1S) -> pi(+) pi(-) pi(0), K-*(892)(0)(K) over bar (0) + c.c., and Upsilon(2S) -> K-S(0) K+ pi(-) + c.c. Branching fractions are measured for all the processes, while 90% confidence level upper limits on the branching fractions are also set for the modes with a statistical significance of less than 3 sigma. The ratios of the branching fractions of Upsilon(2S) and Upsilon(1S) decays into the same final state are used to test a perturbative QCD prediction for Okubo-Zweig-Iizuka- suppressed bottomonium decays.