Speaker
Description
The meson photoproduction is a useful tool to study baryon resonances.Especially, an $\eta$ meson is an isoscalar meson with $s\bar{s}$ components, so it is expected to couple with $\mathrm{N}^{*}$ states with large $s\bar{s}$ components. In previous experiments, the bump structure was seen above 2 GeV in differential cross sections of $\eta$ photoproduction. But in this energy region, many resonance states exist, so it is difficult to distinguish each contribution by just measuring the differential cross sections. Therefore, it is necessary to measure the photon beam asymmetry, which is one of the spin observables.
The experiment was carried out in the LEPS2 beamline at SPring-8 using GeV photon beam. This photon beam is highly linear polarized, and this polarization degree is more than 90 $\%$ in high energy regions. Produced particles were measured using the BGOegg calorimeter and the forward chambers. The photon beam asymmetries above 2.1 GeV were measured for the first time. We report the experimental results and comparisons with the partial wave analysis.
