  A Bethe-Salpeter treatment of Cooper pairs (CPs) based on an ideal Fermi gas
(IFG) "sea"' yields the familiar negative-energy, two-particle bound-state if
two-hole CPs are ignored, but is meaningless otherwise as it gives
purely-imaginary energies. However, when based on the BCS ground state,
legitimate two-particle "moving" CPs emerge but as positive-energy,
finite-lifetime resonances for nonzero center-of-mass momentum, with a
\textit{linear}dispersion leading term. Bose-Einstein condensation of such
pairs may thus occur in exactly two dimensions as it cannot with quadratic
dispersion.
