Near-threshold incoherent pion photoproduction on the deuteron with final-state interaction effects

Incoherent pion photoproduction on the deuteron gamma d -> pi NN is investigated in the energy region E-gamma(thr) <= E-gamma <= 160 MeV. The model applied contains the amplitudes of the impulse approximation as well as the NN and pi N rescattering in the final state. For the elementary gamma N -> pi N amplitude, the unitary isobar MAID-2007 model is used. This model is parameterized in terms of invariant amplitudes and allows one to give a more reliable description of the threshold region. The half-off-shell NN and pi N scattering amplitudes are obtained from separable representations of realistic NN and pi N interactions, respectively. For the first time, numerical results for the linear photon asymmetry Sigma, vector T-11 and tensor T-2M (M = 0, 1, 2) deuteron spin asymmetries for the reactions gamma d -> pi(-) pp, gamma d -> pi(+)nn, and gamma d -> pi(0) np are presented. In addition, results for the unpolarized differential and total cross sections are given. We found that the influence of NN rescattering is moderate in both charged-and neutral-pion production channels, whereas pi N rescattering is almost negligible in the charged-pion production channels which is not the case in neutral-pion production since a noticeable contribution is obtained. The calculated results for unpolarized differential and total cross sections are compared with the available experimental data and other theoretical models, and a satisfactory agreement is obtained. (C) 2019 Elsevier Inc. All rights reserved.