Effects of meson-exchange currents on the (e→,e’p) structure functions

The response functions for the unpolarized (e,e’p) and polarized (e→,e’p) reaction are calculated for medium-heavy nuclei under quasifree conditions. The formalism presented here incorporates both electron distortion effects and two-body currents related to meson-exchange and the Δ(1232) excitation. The final-state interaction of the outgoing nucleon with the residual nucleus is handled in a self-consistent Hartree-Fock random phase approximation formalism. The effect of Coulomb distortion of the incoming and outgoing electron is included within a fully distorted wave calculation. The sensitivity of the results to the two-body currents is discussed for the five structure functions in quasielastic (e→,e’p) scattering off the target nuclei ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$. A selective sensitivity to the two-body currents is obtained in the longitudinal-transverse interference term ${\mathit{W}}_{\mathit{L}\mathit{T}}$ for which two-body currents can explain part of the discrepancy between the impulse-approximation calculations and the data.