Electron-electron scattering and conductivity of disordered systems with a Galilean-invariant spectrum

The electron--electron scattering does not affect the electrical current in Galilean--invariant systems. We show that nevertheless collisions may contribute to electric resistivity of systems with parabolic spectrum provided they have multiply connected Fermi surface and there is an additional mechanism scattering. To this end, we calculate a two-dimensional electron gas two filled transverse subbands presence impurity Though between electrons do directly such systems, cause redistribution contours, which results noticeable change for realistic mechanisms