  Pairing occurs in conventional superconductors through a reduction of the
electronic potential energy accompanied by an increase in kinetic energy,
indicating that the transition is driven by a pairing potential. In the
underdoped cuprates, optical experiments show that pairing is driven by a
reduction of the electronic kinetic energy. Using the Dynamical Cluster
Approximation we study the nature of superconductivity in a microscopic model
of the cuprates, the two-dimensional Hubbard model. We find that pairing is
indeed driven by the kinetic energy and that superconductivity evolves from an
unconventional, spin-charge separated state, consistent with the RVB model of
high-temperature superconductors.
