The trinucleon charge form factors are studied for various nuclear interaction models with possible three-body force and meson-exchange-current effects included. A unitary transformation method of generating three-body forces is discussed. Various meson-exchange effects, including pair and recoil currents as well as that of the $\pi \mathrm{NN}$ vertex function, are investigated. The calculations show that the strong potential dependence of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ charge form factor in the impulse approximation diminishes considerably when meson-exchange effects are included. Exchange effects in ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ are smaller than in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and do not reduce the potential dependence. By including meson-exchange currents and three-body forces, good fits to the available ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ form factor data for $0.5 {\mathrm{fm}}^{-2\mathrm{}}\le q^2\le 12 {\mathrm{fm}}^{-2\mathrm{}}$ are obtained without sacrificing a satisfactory triton binding energy. The position of the diffraction minimum is correctly predicted and the height of the second maximum is improved to about half of the experimental value.

NUCLEAR STRUCTURE ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^3{}_{}{}^{}\mathrm{H}$; calculated charge form factors; pair and recoil exchange currents included; effect of $\pi \mathrm{NN}$ vertex function; dependence on nuclear force; six two-body forces, two three-body forces.

• Received 9 August 1976

DOI:https://doi.org/10.1103/PhysRevC.15.404