Abstract / Description of output
The reactions gamma p -> eta p and gamma p -> eta'p are measured from their thresholds up to the center-of-mass energy W = 1.96 GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section for eta photoproduction at the energies in the vicinity of the eta' threshold, W = 1896 MeV (E-gamma = 1447 MeV). Within the framework of a revised eta MAID isobar model, the cusp, in connection with a steep rise of the eta' total cross section from its threshold, can only be explained by a strong coupling of the poorly known N(1895)1/2(-) state to both eta p and eta' p. Including the new high-accuracy results in the eta MAID fit to available eta and eta' photoproduction data allows the determination of the N(1895)1/2(-) properties.
Keywords / Materials (for Non-textual outputs)