NN Final-State Interaction in the Helicity Dependence of Inclusive - Photoproduction from the Deuteron

The helicity dependence of the inclusive $\pi^-$ photoproduction reactionfrom the deuteron in the $\Delta$(1232)-resonance region is investigated withinclusion of final-state nucleon-nucleon rescattering ($NN$-FSI). For theelementary $\pi$-production operator an effective Lagrangian model whichincludes the standard pseudovector Born terms and a contribution from the$\Delta$-resonance is used. The half-off-shell $NN$-scattering matrix isobtained from a separable representation of a realistic $NN$-interaction. Thedifferential polarized cross-section difference for parallel and antiparallelhelicity states is predicted and compared with experiment. We find that theeffect of $NN$-FSI is much less important in the helicity difference than inthe previously studied unpolarized differential cross section. Furthermore, thecontribution of $\vec d(\vec\gamma,\pi^-)pp$ to the deuteron spin asymmetry isexplicitly evaluated with inclusion of $NN$-FSI. It has been found that theeffect of $NN$-FSI is much larger in the asymmetry than in the total crosssection, and this leads to an appreciable reduction of the spin asymmetry inthe $\Delta$-region. Inclusion of such effect also leads to improved and quitesatisfactory agreement with existing experimental data.Comment: 13 pages, 6 eps figures, published in Prog. Theor. Phys. 113 (2005) 169-18