Massive Fields of Arbitrary Half-Integer Spin in Constant   Electromagnetic Field
  We study the interaction of gauge fields of arbitrary half-integer spins with the homogeneous electromagnetic field. We reduce the problem of obtaining the gauge-invariant Lagrangian and transformations of the half-integer spin fields in the external field to an algebraic problem of search for a set of operators with certain algebraical features using the representation of the higher-spin fields as vectors in a pseudo-Hilbert space. We consider such construction at linear order in the external electromagnetic field and also present an explicit form of interaction Lagrangians and gauge transformations for the massive particles of spins 3/2 and 5/2 in terms of symmetric spin-tensor fields. The obtained result is valid for space-time of arbitrary even dimension. 
S.M. Klishevich