Normal state property of the t-J model
  Using the spin-hole coherent state representation and taking a long range antiferromagnetic N\`{e}el order as a background of the localized spin degree part, we have studied the normal state behavior of the t-J model, and shown that a strongly short-range antiferromagnetic correlation of the localized spin degree part is responsible for the anomalous non-Korringa-like relaxation behavior of the planar copper spin, the Korringa-like behavior of the planar oxygen spin may derive from the charge degree part describing a Zhang-Rice spin-singlet; The charge degree part feels a strongly staggered magnetic field induced by this short-range antiferromagnetic correlation as a doping hole hopping, this staggered magnetic field enforces the charge degrees to have different responses to external magnetic and electric fields and to show two relaxation rate behaviors corresponding to the planar resistivity and Hall angle, respectively. We have found that the temperature dependence of magnetoresistance is $T^{-n}$, $n\simeq 3$, near the optimal doping, $n\simeq 4$, in the underdoping region, violating Kohler's rule, the transport relaxation rate is of the order of $2k_{B}T$, all that are consistent with the normal state of the cuprate superconductors. 
Yu-Liang Liu (ICTP, Trieste)