Speaker
Description
We carry out hadron photoproduction experiments at E$\gamma$=1.5-3.0 GeV at SPring-8/LEPS. We took charged pion data on the proton at forward angles for the first time and the data were analyzed recently. The differential cross sections for the $\pi^{-}\Delta^{++}$ and $\pi^{+}\Delta^{0}$ reactions are compared. In the $\pi^{-}\Delta^{++}$ reaction $\bar{u}u$ is produced, while in the $\pi^{+}\Delta^{0}$ reaction $\bar{d}d$ is produced. If the isospin=1 exchange in the t-channel is dominant, the cross section ratio $\sigma$($\pi^{+}\Delta^{0}$)/$\sigma$($\pi^{-}\Delta^{++}$) becomes 1/3. Preliminary experimental cross section ratios are close to 1/3 at small $\pi$ angles, while they are larger than 1/3 at large $\pi$ angles. Larger ratios suggest that the $\bar{d}d$ production is enhanced compared with the $\bar{u}u$ production. This result might be a hint to clarify the pion photoproduction reactions.
We also report recent physics results in our group.
We are developing a polarized HD target and large acceptance spectrometer for near future experiments. The present status of these developments is also reported.
