  The average persistent current <I> of diffusive electrons in the Hartree-Fock
approximation is derived in a simple non-diagrammatic picture. The Fourier
expansion directly reflects the winding number decomposition of the diffusive
motion around the ring. One recovers the results of Ambegaokar and Eckern, and
Schmid. Moreover one finds an expression for <I> which is valid beyond the
diffusive regime.
