  A phenomenological description of the high-Tc superconductors based on the
Cooperon propagator is presented. This model allows one to study the effects of
local pairing correlations and long-range phase fluctuations on the same
footing, both above and below Tc. Based on numerical calculations, it is shown
that the two types of correlations contribute to the gap/pseudogap in the
single-particle excitation spectra. The concourse of these two effects can
induce low energy states, which should be observable in underdoped materials at
very low temperature.
