The nonrelativistic approximation for a spin 3/2 particle in gravitation field

In the paper, a new and simple approach to derive the nonrelativistic equation for a spin 3/2 particle in presence of external electromagnetic and gravitational fields is proposed. It is based on the initial relativistic equation and the general method to determine the large and small components of the wave function in the non-relativistic limit with the use of projective operator method. First The problem is first solved in Minkowsly space, after that this approch is extended to curved space-time background.