Nearly Localised States in Weakly Disordered Conductors. II. Beyond Diffusion Approximation

We use optimal fluctuation method for a new ballistic σ -model to study the long time dispersion of conductance G ( t ) of a mesoscopic sample. In the long time limit the conductance of a d -dimensional sample decays as exp (cid:0) − A ln d t (cid:1) . At shorter times the new results match those in our previous paper [1]. It is found that at very long times the diffraction effects are important and the ballistic treatment is not valid. We also suggest a physical picture of trapping.