  We investigate the theory of particles with arbitrary spin and anomalous
magnetic moment in the Lorentz representation (0,s)X(s,0), in an external
constant and uniform electromagnetic field. We obtain the density matrix of
free particles in pure spin states. The differential probability of pair
producing particles with arbitrary spin by an external constant uniform
electromagnetic field has been found using the exact solutions. We have
calculated the imaginary and real parts of the Lagrangian in an electromagnetic
field that takes into account vacuum polarization.
