Backward-angle photoproduction of $\omega$ and ${\eta }^{\mathrm{\prime }}$ mesons from protons at $E_{\gamma }=1.5-3.0$ GeV

We report the measurement of differential cross sections for $\omega$ and ${\eta }^{\mathrm{\prime }}$ photoproduction from protons at backward angles ($-1.0<\cos {\mathrm{\Theta }}_{C\mathrm{.}M}^X<-0.8$) using linearly polarized photons at $E_{\gamma }=$$1.5-3.0$ GeV. Differential cross sections for $\omega$ mesons are larger than the predicted $u$-channel contribution in the energy range $2.0\le \sqrt{s}\le 2.4$ GeV. The differential cross sections for $\omega$ and ${\eta }^{\mathrm{\prime }}$ mesons become closer to the predicted $u$-channel contribution at $\sqrt{s}>2.4$ GeV. A bump structure in the $\sqrt{s}$ dependence of the differential cross sections for ${\eta }^{\mathrm{\prime }}$ mesons was observed at $\sqrt{s}\sim$2.35 GeV.