The effect of electron correlation on the superconducting and normal   properties of the cuprates
  The strong electron correlation in the cuprates can lead to an enhanced effective mass for both bosonic and fermionic quasiparticles. Where this correlation is characterized by a length that is inversely proportional to the effective temperature, the thermal wavelength for the bosonic quasiparticles becomes essentially independent of temperature. Applying this concept to a preformed pair model, such as the (Cu)13 cluster model, gives Tc vs dopant curves and superconducting gaps in good agreement with experiment. In addition, a correlation-enhanced effective mass provides a natural explanation for the anomalous normal state resistivity and optical conductivity of the cuprates. 
A. Rosencwaig