Study of high momentum η′ production in B → η′Xs

We measure the branching fraction for the charmless semi-inclusive process B→η′Xs, where the η′ meson has a momentum in the range 2.0 to 2.7  GeV/c in the Υ(4S) center-of-mass frame and Xs represents a system comprising a kaon and zero to four pions. We find B(B→η′Xs)=[3.9±0.8(stat)±0.5(syst)±0.8(model)]×10-4. We also obtain the Xs mass spectrum and find that it fits models predicting high masses.