Beam Asymmetry \(\mathbf{\Sigma}\) for the Photoproduction of \(\mathbf{\eta}\) and \(\mathbf{\eta^{\prime}}\) Mesons at \(\mathbf{E_{\gamma}=8.8}\)GeV

Abstract

We report on the measurement of the beam asymmetry \(\Sigma\) for the reactions \(\vec{\gamma}p\rightarrow p\eta\) and \(\vec{\gamma}p \rightarrow p\eta^{\prime}\) from the GlueX experiment, using an 8.2--8.8 GeV linearly polarized tagged photon beam incident on a liquid hydrogen target in Hall D at Jefferson Lab. These measurements are made as a function of momentum transfer \(-t\), with significantly higher statistical precision than our earlier \(\eta\) measurements, and are the first measurements of \(\eta^{\prime}\) in this energy range. We compare the results to theoretical predictions based on \(t\)--channel quasi-particle exchange. We also compare the ratio of \(\Sigma_{\eta}\) to \(\Sigma_{\eta^{\prime}}\) to these models, as this ratio is predicted to be sensitive to the amount of \(s\bar{s}\) exchange in the production. We find that photoproduction of both \(\eta\) and \(\eta^{\prime}\) is dominated by natural parity exchange with little dependence on \(-t\).