Search for B-s(0) -> eta'Xs(s)over-bar at Belle using a semi-inclusive method

We report the first search for the penguin-dominated process Bs0→η′Xss¯ using a semi-inclusive method. A 121.4 fb-1 integrated luminosity ϒ(5S) data set collected by the Belle experiment, at the KEKB asymmetric-energy e+e- collider, is used. We observe no statistically significant signal and, including all uncertainties, we set a 90% confidence level upper limit on the partial branching fraction at 1.4×10-3 for M(Xss¯)≤2.4 GeV/c2.