  Massive spin 1/2 particles require 2-spinors for rotations, 4-spinors for
rotations and boosts with parity. Including translations requires 8-spinors.
Adapting 4-spinor field theory to 8-spinor fields with translation symmetry is
discussed here. It is shown that four of these spin components act like
conventional 4-spinors, satisfying the conventional free-particle Dirac
equation. The remaining four components have unconventional coordinate
dependence due to translation symmetry. One finds that the 4-vector current of
the 8-spinor is proportional to the electromagnetic 4-vector potential of the
conventional 4-spinor, with arbitrary charge. Thus translation symmetry in
field theory unites a conventional 4-spinor field and its electromagnetic
vector potential.
