Path Integral Description of Normal State Transport in High Tc Superconductors

I present a path integral approach to the problem of the time retarded interactions between polarons and double well potentials in systems with lattice instabilities, i.e. high Tc superconductors. It is shown that the c-axis electrical resistivity depends linearly on temperature for intermediate values of the overall electron-phonon coupling whereas strong anharmonicity induces a non metallic behavior as a consequence of trapping of the charge carriers.