Measurements of the Branching Fractions of Exclusive Charmless $\mathit{B}$ Meson Decays with ${\eta }^{\prime }$ or $\omega$ Mesons

We present the results of searches for $B$ decays to charmless two-body final states containing ${\eta }^{\prime }$ or $\omega$ mesons, based on $20.7{\mathrm{fb}}^{-1\mathrm{}}$ of data collected with the BABAR detector. We find the branching fractions $B(B^{+}\to {\eta }^{\prime }{K}^{+})=(70\pm 8\pm 5)\times {10}^{-6\mathrm{}}$, $B(B^0\to {\eta }^{\prime }{K}^0)=({42}_{-11\mathrm{}}^{+13\mathrm{}}\pm 4)\times {10}^{-6\mathrm{}}$, and $B(B^{+}\to \omega {\pi }^{+})=({6.6}_{-1.8\mathrm{}}^{+2.1\mathrm{}}\pm 0.7)\times {10}^{-6\mathrm{}}$, where the first error quoted is statistical and the second is systematic. We give measurements of four additional modes for which the $90\%$ confidence level upper limits are $B(B^{+}\to {\eta }^{\prime }{\pi }^{+})<12\mathrm{}\times {10}^{-6\mathrm{}}$, $B(B^{+}\to \omega K^{+})<4\mathrm{}\times {10}^{-6\mathrm{}}$, $B(B^0\to \omega K^0)<13\mathrm{}\times {10}^{-6\mathrm{}}$, and $B(B^0\to \omega {\pi }^0)<3\mathrm{}\times {10}^{-6\mathrm{}}$.