Vector particle in a constant magnetic field

Relativistic equations of a vector field in an external magnetic field are investigated. To a certain extent an arbitrary choice of vector field Lagrangian in an external magnetic field permits to introduce phenomenological parameter K characterizing magnetic moment of a particle. A case K=1 corresponds to the Weinberg model. Exact solutions of vector equations both in the case K=1 and for arbitrary K have been obtained. Spin states of particles are considered. Energy spectrum of a vector particle in the magnetic field which agree with earlier known results has been determined