  In the context of the nonminimal Standard-Model Extension a special subset of
the CPT-even higher-dimensional operators in the photon sector is discussed
from a quantum-field theoretical point of view. The modified dispersion laws,
photon polarization vectors plus the gauge field propagator are obtained and
their properties are analyzed. It is demonstrated that for certain sectors of
the modified theory a puzzle arises for the optical theorem at tree-level. This
is followed by a discussion of how it can be interpreted and resolved at first
order Lorentz violation. Furthermore the commutator of two gauge fields that
are evaluated at different spacetime points is obtained and discussed. The
structure of the theory is shown to resemble the structure of the modification
based on the corresponding dimension-4 operator. However some properties are
altered due to the nonrenormalizable nature of the theory considered. The
results provide more insight into the characteristics of Lorentz-violating
quantum field theories that rest upon contributions of nonrenormalizable
dimension.
