Observation of High Momentum<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="italic">η</mml:mi></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>Production in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">B</mml:mi></mml:math>Decays

We report the first observation of $B\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}X$ transitions with high momentum ${\ensuremath{\eta}}^{\ensuremath{'}}$ mesons. We observe $39.0\ifmmode\pm\else\textpm\fi{}11.6B$ decay events with $2.0&lt;{p}_{{\ensuremath{\eta}}^{\ensuremath{'}}}&lt;2.7\phantom{\rule{0ex}{0ex}}\mathrm{GeV}/c$, the high momentum region where background from $b\ensuremath{\rightarrow}c$ processes is suppressed. We discuss the physical interpretation of the signal, including the possibility that it is due to $b\ensuremath{\rightarrow}{\mathrm{sg}}^{*}$ transitions. Given that interpretation, we find $B(B\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{X}_{s})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}[6.2\ifmmode\pm\else\textpm\fi{}1.6(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.3(\mathrm{syst}{)}_{\ensuremath{-}1.5}^{+0.0}(\mathrm{bkg})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ for $2.0&lt;{p}_{{\ensuremath{\eta}}^{\ensuremath{'}}}&lt;2.7\phantom{\rule{0ex}{0ex}}\mathrm{GeV}/c$.