Near-threshold electroproduction of positive pions on a deuteron

Pion electroproduction on a deuteron has been considered in the approach based on the unitary-transformation method. A generalization of the Siegert theorem has been used to ensure the gauge independence of our calculations. The relationship between the formalism employed in this study and the theory of multiple scattering has been established. Observables of the reaction (d) over right arrow ((e, e'pi+)nn) featuring vectorially polarized deuterons have been calculated near the reaction threshold by means of the proposed approach. The computed structure functions are contrasted against the corresponding results obtained in the impulse approximation.