EFFECTS OF RESCATTERING OF PIONS IN THE REACTION GAMMA-D-]D-PI-0 AND THE PROBLEM OF DIBARYON RESONANCES

Pion-rescattering effects are studied in coherent production of neutral pions in the reaction gammad --> dpi0. The hypothesis of factorization of the amplitudes of the reactions gammaN --> Npi and piN --> Npi and of the deuteron form factors in calculating the amplitude of the reaction gammad --> dpi0 is reasonable in a wide range of photon energies 0.3 less-than-or-equal-to E(gamma) less-than-or-equal-to 1 GeV and small angles theta (theta < 90-degrees). Inclusion of rescattering effects in this kinematic region improves significantly the agreement between the theory and the existing experimental data. However, such a model does not work in the region of large angles theta (theta > 90-degrees). Therefore, it is difficult to interpret uniquely the experimental data in this angular range in order to clarify the role of dibaryon resonances.