Solution of the Fisk--Tait equation for spin-3/2 particles in interaction with a homogeneous magnetic field

The Fisk--Tait wave equation for spin-3/2 particles, which has been shown to remain causal even with coupling to external fields, is shown to be also free of other types of difficulties by which the Rarita--Schwinger formalism is plagued. Unlike the latter, the Fisk----Tait equation with coupling to a homogeneous magnetic field has no modes with complex frequencies irrespective of the magnetic field strength. We show this by explicit solution of the equation. Further, the invariant scalar product in the Fisk-Tait theory, expressed in terms of the independent components of the wave function, is shown to be unaffected by the presence of the external field