SELF-ENERGY AND PERSISTENT CURRENT IN ENSEMBLES OF MESOSCOPIC METAL RINGS

The average persistent current in a grand canonical ensemble of mesosc opic metal rings threaded by a magnetic flux in the diffusive regime i s related to the presence of a component of the electronic self-energy , which is odd with respect to the electron velocity. In a non-interac ting model, the ''velocity-odd'' component of the self-energy is found to be exponentially small. Including the Coulomb interaction between electrons, a finite velocity-odd component of the self-energy is obtai ned. A simple model is presented, which exhibits the essential feature s of the phenomenon.