  By recognizing the vital importance of two-hole Cooper pairs (CPs) in
addition to the usual two-electron ones in a strongly-interacting many-electron
system, the concept of CPs was re-examined with striking conclusions. Based on
this, Bose-Einstein condensation (BEC) theory has been generalized to include
not boson-boson interactions (also neglected in BCS theory) but rather
boson-fermion (BF)interaction vertices reminiscent of the Frohlich
electron-phonon interaction in metals. Unlike BCS theory, the GBEC model is not
a mean-field theory restricted to weak-coupling as it can be diagonalized
exactly. In weak coupling it reproduces the BCS condensation energy. Each kind
of CP is responsible for only half the condensation energy. The GBEC theory
reduces to all the old known statistical theories as special cases including
the so-called "BCS-Bose crossover" picture which in turn generalizes BCS theory
by not assuming that the electron chemical potential equals the Fermi energy.
Indeed, a BCS condensate is precisely the weak-coupling limit of a GBE
condensate with equal numbers of both types of CPs. With feasible Cooper/BCS
model interelectonic interaction parameter values, and even without BF
interactions, the GBEC theory yields transition temperatures [including
room-temperature superconductivity (RTSC)] substantially higher than the BCS
ceiling of around 45K, without relying on non-phonon dynamics involving
excitons, plasmons, magnons or otherwise purely-electronic mechanisms.
