Darwin-Foldy term and proton charge radius

In this contribution we study the Dirac equation for a finite size proton in an external electric field with explicit introduction of Dirac-Pauli form factors. Our aim is twofold. On the one hand, we wish to study whether our conclusions regarding the exact cancellation between Dirac form factor and Foldy term contributions occurring for the neutron still hold for the proton. On the other hand, we wish to clearly illustrate some of the specific features of the description of a composite particle like the proton with the Dirac equation.Comment: contribution to XVIIth European Conference of Few-Body Problems in Physics, Evora, Portugal Sept 2000, to be published in Nucl. Phys.

Reworking the Tucson-Melbourne Three-Nucleon Potential

We introduce new values of the strength constants (i.e., $a$, $b$, $c$, and $d$ coefficients) of the Tucson-Melbourne (TM) 2$\pi$ exchange three nucleon potential. The new values come from contemporary dispersion relation analyses of meson factory $\pi$N scattering data. We make variational Monte Carlo calculations of the triton with the original and updated three-body forces to study the effects of this update. We remove a short-range -- $\pi$-range part of the potential due to the $c$ coefficient and discuss the effect on the triton binding energy.Comment: 12 pages, to appear in Few-Body System