ELECTRON-ELECTRON SCATTERING RATE IN DISORDERED MESOSCOPIC SYSTEMS

The inelastic quasiparticle lifetime due to the electron-electron inte raction (out-scattering time in the kinetic equation formalism) is cal culated for finite metallic diffusive systems (quantum dots) in the wh ole range of parameters. Both cases of ''continuous'' (the inelastic l evel broadening much exceeds the mean level spacing) and ''discrete'' spectrum are analyzed. In particular, the crossover between one- and z ero-dimensional regimes is studied in detail. In the case of a continu ous spectrum the out-scattering time is shown to be the same as the in elastic time entering expressions for universal conductance fluctuatio ns and persistent currents. It is also found to be shorter than the ph ase-breaking time in two- and one-dimensional systems, while in zero-d imensional systems these two times coincide. In the case of a discrete spectrum for small enough systems a universal behavior of the scatter ing time is obtained. For temperatures below the mean level spacing th e out-scattering rate is shown to be vanishingly small.