Electromagnetic structure of trinucleons

Abstract

The electromagnetic form factors of the trinucleons ${}^{3}\mathrm{H}$ and ${}^{3}\mathrm{He}$ are calculated with wave functions obtained with the Argonne ${v}_{18}$ two-nucleon and Urbana IX three-nucleon interactions. Full account is taken of the two-body currents required by current conservation with the ${v}_{18}$ interaction as well as those associated with $N\ensuremath{\Delta}$ transition currents and the currents of \ensuremath{\Delta} resonance components in the wave functions. Explicit three-nucleon current operators associated with the two-pion exchange three-nucleon interaction arising from irreducible $S$-wave pion-nucleon scattering are constructed and shown to have very little effect on the calculated magnetic form factors. The calculated magnetic form factor of ${}^{3}\mathrm{H},$ and charge form factors of both ${}^{3}\mathrm{H}$ and ${}^{3}\mathrm{He}$ are in satisfactory agreement with the experimental data. However, the position of the zero in the magnetic form factor of ${}^{3}\mathrm{He}$ is slightly underpredicted.