2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/151820We have generalized the scattering-matrix theory of multiple Andreev reflections in mesoscopic Josephson junctions to the multi-mode case, and applied it to short superconductor/normal metal/superconductor junctions with diffusive electron transport. Both the dc and ac current-voltage characteristics are analyzed for a wide range of bias voltages $V$. For voltages smaller than the supeconducting gap the dc differential conductance of the junction diverges as $1/\sqrt{V}$.14 pages, RevTex, 5 postscript figuresSuperconductivityMesoscale and Nanoscale Physicstext