SUPERCONDUCTIVITY BEYOND MIGDAL THEOREM AND HIGH-T(C) PHENOMENOLOGY

Many properties of the superconducting state of high-T(c) materials ha ve been interpreted within the Eliashberg framework with a very large coupling (lambda greater-than-or-equal-to 3). Here we point out that t he inclusion of non-adiabatic corrections acts as an effective couplin g for various properties that can, therefore, be reproduced with a muc h smaller coupling (lambda almost-equal-to 1) within the generalized t heory. This can provide a new perspective for the analysis of supercon ductivity data with moderate couplings but within a theory that goes b eyond Migdal's theorem.