Contribution of Coherent Neutral-Pion Photoproduction Channel to the Gerasimov-Drell-Hearn Sum Rule for the Deuteron

Abstract

The helicity dependence of the (gamma) over right arrow reaction channel is studied for incident photon energies from threshold up to the A( l 232)-resonance using an enhanced elementary pion photoproduction operator and a realistic high-precision potential for the deuteron wave function. The doubly polarized total cross sections for parallel and antiparallel helicity states are predicted. Then the contribution to the deuteron spin asymmetry is calculated. In addition, the contribution to the Gerasimov-Drell-Hearn (GDH) integral is evaluated by explicit integration up to a photon lab-energy of 350 MeV. The sensitivity of the results to the elementary pion photoproduction amplitude and the potential model used for the deuteron wave function is also investigated. Considerable dependence of the results on both the elementary amplitude and the deuteron wave function is found. We expect that these results may be useful to interpret the recent measurements from A2 and GDH @MAMI Collaborations.