A state of KEK in pion photoproduction from a view point of phenomenological analysis

A part of KEK (High Energy Accelerator Research Organization) in the pion photoproduction was investigated by the analytical results of Metcal-Waker (M-W) paper and Nagoya paper, which used phenomenological analysis. KEK data were obtained from the data bunk:'Data Compilation of Single Pion Photoproduction below 2 GeV'. As KEK data lied weight on polarization phenomena, we studied three polarization phenomena such as recoil nucleon polarization (P), polarized beam asymmetry (Σ) and polarized target asymmetry (T). The analytical results are summarized as followings; 1) on γp→π-n, the contribution of KEK data is T only. Energy excitation calculation showed the accuracy did not corresponded to the number of data. However, Angular distribution calculation showed the accuracy was better than number of data by MW analysis and Nagoya analysis. 2) On γp→π0p, the accuracy of T and dσ/dΩ data corresponded to the number of data. But, the accuracy of P data did not correspond to the number of data. 3) On γn→πp, the accuracy of P data was better than the number of data and Σ data corresponded to the number. However, T did not correspond the accuracy to the number of data. 4) Recently, BNL measured the angular distribution of γp→π-n and γp→π0p, between 210 and 330 MeV, and the accuracy of Σ was less than 1%. The future experiments of pion photoproduction in Japan were discussed. (S.Y.)