We find that the three-body two-pion-exchange currents lead to an effect very similar to that of the two-body one-pion-exchange currents on the charge form factors of ${}_{}{}^3{}_{}{}^{}\mathrm{H}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. Most of this effect is, however, canceled by similar $\rho$-meson-exchange currents. The four-body three-meson-exchange currents are of negligible importance for the α-particle charge form factor.

NUCLEAR REACTIONS ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^3{}_{}{}^{}\mathrm{H}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}(e,e)$; calculated charge form factors with 2-, 3-, and 4-body meson-exchange operators; pion exchange with/without $\rho$ exchange; simple wave functions; effects of correlations, vertex factors.

• Received 25 April 1977

DOI:https://doi.org/10.1103/PhysRevC.16.2105