Recovery of the persistent current induced by the electron-electron   interaction in mesoscopic metallic rings
  Persistent currents in mesoscopic metallic rings induced by static magnetic fields are investigated by means of a Hamiltonian which incorporates diagonal disorder and the electron-electron interaction through a Hubbard term ($U$). Correlations are included up to second order perturbation theory which is shown to work accurately for $U$ of the order of the hopping integral. If disorder is not very strong, interactions increase the current up to near its value for a clean metal. Averaging over ring lengths eliminates the first Fourier component of the current and reduces its value, which remains low after interactions are included. 
G. Chiappe (Departamento de F\'isica, Universidad de Buenos Aires,   Pabell\'on {I}, Buenos Aires, Argentina), J.A. Verg\'es...