Many-body exchange currents and the tri- and four-nucleon charge form factors

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.