Helicity Dependence of the \vec\gamma\vec N \to \pi N Reaction Channels in the \Delta-Resonance Region


Abstract: Based on a prior effective Lagrangian model on single pion photoproduction from the nucleon, successfully tested in total and differential cross sections, the helicity dependence from the interaction of circularly polarized photons and a longitudinally polarized nucleon target is studied in the energy range from \pi-threshold through the \Delta(1232)-resonance region. The doubly polarized total and differential cross section differences for parallel \sigma^{3/2} and antiparallel \sigma^{1/2} helicity states are predicted and compared with recent experimental data. We show that the results are sensitive to interferences among different contributions to the process and, thus, represent a complementary test of the theoretical model. A quite satisfactory agreement with recent experimental data from the GDH-collaboration is obtained.

Keywords: photoproduction reactions, meson production, polarization phenomena in reactions.

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