Observation of High Momentum ${\mathit{\eta }}^{\prime }$ Production in $\mathit{B}$ Decays

We report the first observation of $B\to {\eta }^{\prime }X$ transitions with high momentum ${\eta }^{\prime }$ mesons. We observe $39.0\pm 11.6B$ decay events with $2.0<\mathrm{}{p}_{{\eta }^{\prime }}<2.7\mathrm{GeV}/c$, the high momentum region where background from $b\to c$ processes is suppressed. We discuss the physical interpretation of the signal, including the possibility that it is due to $b\to {\mathrm{sg}}^{*}$ transitions. Given that interpretation, we find $B(B\to {\eta }^{\prime }{X}_s)=[6.2\pm 1.6(\mathrm{stat})\pm 1.3(\mathrm{syst}{)}_{-1.5\mathrm{}}^{+0.0\mathrm{}}\left(\mathrm{bkg}\right)]\times {10}^{-4\mathrm{}}$ for $2.0<\mathrm{}{p}_{{\eta }^{\prime }}<2.7\mathrm{GeV}/c$.