Spinning Particle with Anomalous Magnetic Moment in an External Plane   Wave Field
  In this paper we study the interaction of a Dirac-Pauli particle with an electromagnetic plane wave, by using a previously given generalization of the pseudo-classical Lagrangian for a spinning particle with an anomalous magnetic moment. We derive the explicit expressions for the eigenfunctions and the Green's functions of the theory. We discuss the validity of the semi-classical approach by comparing the wavefunctions with the (pseudo)-classical solutions of the Hamilton-Jacobi equation. 
A. Barducci, R. Giachetti