We study the evolution of the optical conductivity in the t-J model with
temperature and doping using the Extended Dynamical Cluster Approximation. The
cluster approach results in an optical mass which is doping independent near
half filling. The transition to the superconducting state in the overdoped
regime is characterized by a decrease in the hole kinetic energy, in contrast
to the underdoped side where kinetic energy of holes increases upon superfluid
condensation. In both regimes, the optical conductivity displays anomalous
transfers of spectral weight over a broad frequency region.Comment: 4 pages, 3 figure
