Abstract
The helicity-dependent coherent pi(0)-photoproduction in the reaction gamma d ->pi(0)d near the eta-threshold is investigated. The calculations are performed within an approach which includes the reaction amplitudes of the impulse approximation (IA), two-step process with intermediate pi N- and eta N-rescattering, and the higher order terms in the multiple scattering series for the intermediate eta NN interaction. The contribution of gamma d ->pi(0)d to the deuteron spin asymmetry is calculated and its contribution to the Gerasimov-Drell-Hearn (GDH) integral is explicitly evaluated by integration up to a photon energy of 900 MeV. In addition, the helicity E-asymmetry is calculated. The results revealed that the doubly polarized differential cross-sections and the helicity E-asymmetry are sensitive to the interference of rescattering effects, specially at photon energies 600-800 MeV and extreme backward pion angles. The sensitivity of the obtained results for the GDH integral to the choice of NN potential model governing the deuteron wave function is discussed. We find that the deviation among results obtained for the deuteron GDH integral using different deuteron wave functions is quite large.