MAGNETIC RESONANCES BETWEEN MASSIVE AND MASSLESS SPIN-1/2 PARTICLES WITH MAGNETIC-MOMENTS

The general effective radial potentials for a spin-1/2 particle interacting with scalar, electric, and magnetic potentials are given. In the m = 0 limit, it is shown that the magnetic potential provides a well deep enough to confine the massless particle. In particular, there are exact zero-energy solutions in which two of the four components of the massless particle are confined; only two can leak out into the asymptotic region. The scattering amplitude is analytic in the entire j plane, hence consists only of Regge poles. © 1980 American Institute of Physics.