Search for $B_{s}^{0} rightarrow eta^{prime} X_{sbar{s}}$ at Belle using a semi-inclusive method

We report the first search for the penguin-dominated process $B_{s}^{0} rightarrow eta^{prime} X_{sbar{s}}$ using a semi-inclusive method. A 121.4 $mathrm{fb}^{-1}$ integrated luminosity $Upsilon(5S)$ 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 $times$ 10$^{-3}$ for $M(X_{sbar{s}})$ $leq$ 2.4 GeV/$c^{2}$.