  In this note we show that a "dynamical" interaction for arbitrary spin can be
constructed in a straightforward way if gauge and Lorentz transformations are
placed on the same foundation. As Lorentz transformations act on space-time
coordinates, gauge transformations are applied to the gauge field. Placing
these two transformations on the same ground means that all quantized field
like spin-1/2 and spin-3/2 spinors are functions not only of the coordinates
but also of the gauge field components. This change of perspective solves a
couple of problems occuring for higher spin fields like the loss of causality,
bad high-energy properties and the deviation of the gyromagnetic ratio from its
constant value g=2 for any spin, as caused by applying the minimal coupling.
Starting with a "dynamical" interaction, a non-minimal coupling can be derived
which is consistent with causality, the expectation for the gyromagnetic ratio,
and well-behaved for high energies. As a consequence, on this stage the
(elektromagnetic) gauge field has to be considered as classical field.
Therefore, standard quantum field theory cannot be applied. Despite this
inconvenience, such a common ground is consistent with an old dream of
physicists almost a century ago. Our approach, therefore, indicates a
straightforward way to realize this dream.
