Near-threshold electroproduction of positive pions on a deuteron

Pion electroproduction on a deuteron has been considered in the approach ba sed on the unitary-transformation method. A generalization of the Siegert t heorem has been used to ensure the gauge independence of our calculations. The relationship between the formalism employed in this study and the theor y of multiple scattering has been established. Observables of the reaction (d) over right arrow ((e, e'pi+)nn) featuring vectorially polarized deutero ns have been calculated near the reaction threshold by means of the propose d approach. The computed structure functions are contrasted against the cor responding results obtained in the impulse approximation.