Photoproduction for N^* and Related Topics at LEPS/LEPS2

Abstract

We have been carrying out photoproduction experiments by using polarized photon beams with energies of 1.5-3 GeV at the LEPS beamline of SPring-8 since 2000. The study of N * is one of the main physics subjects. Several bump structures suggesting N * and ∆ * are observed in the γp → K + Λ, (1520), ηp, and ωp reactions. We newly took charged pion data with high momenta at forward pion angles in 2007. The γp → π + n, π + ∆ 0 , and π − ∆ ++ reactions are observed clearly. Preliminary cross section ratios of dσ(π + ∆ 0 )/dσ(π − ∆ ++ ) at the most forward pion angles are close to 1/3 which is expected from the Clebsch-Gordan coefficients with the isospin 1 exchange in the t-channel. The ratios become larger than 1/3 at larger pion angles at high energies. It is interesting that the dd production is found to be enhanced compared with the uū production. We are developing a polarized hydrogen-deuteride (HD) target and the LEPS2 solenoid spectrometer for complete measurements of all physics observables in the near future experiments.