A nonlocal model of the Yukawa and dipole interactions

By analogy of the nonlocal electromagnetic. interaction of the ring charge, nonlocal Yukawa and dipole interactions are constructed. In this scheme the Yukawa and the dipole potentials and corresponding propagators of massive scalar and massless spinor particles are changed in accordance with the concept of extended particle-strings with a finite size characterized by some length l. It is shown that a formal Euclidean extension of the potential theory is useful for the construction of nonlocal fields and their nonlocal interaction in the Yukawa and dipole theories. In the dipole theory a neutrino like massless spinor particle (nonlocal photon field) carrying a medium range interaction appears. (author)