  In a Euclidean space functional integral treatment of the free energy of QCD,
a chemical potential enters only through the functional determinant of the
Dirac operator which for any flavor is $\dslash + m - \mu_f \gamma_0$ (where
$\mu_f$ is the chemical potential for the given flavor). Any nonzero $\mu$
alters all of the eigenvalues of the Dirac operator relative to the $\mu=0$
value, leading to a naive expectation that the determinant is altered and which
thereby alters the free energy. Phenomenologically, this does not occur at T=0
for sufficiently small $\mu$, in contradiction to this naive expectation. The
problem of how to understand this phenomenological behavior in terms functional
integrals is solved for the case of an isospin chemical through the study of
the spectrum of the operator $\gamma_0 (\dslash + m)$.
