  The detectability of the fermion-potentials appearing in a unified model of
fermions is discussed from the viewpoint of an effective field theory. Although
the fermion-potentials are effectively represented as terms similar to the
$a$-coefficients in the theory of standard-model extension, their magnitudes
are very large and their physical implications are different. A possibility is
shown that the fermion-potentials are detectable by neither the deviations from
conventional energy-momentum conservations, the neutrino-oscillations, the
CPT-violation in neutral meson systems, nor the gravitational effects.
