Comment on "Boson-fermion model beyond the mean-field approximation"
arXiv:cond-mat/9705089 · doi:10.1088/0953-8984/10/13/024
Abstract
In a recent paper [A.S.Alexandrov, J.Phys.:Condens.Matter 8, 6923 (1996); cond-mat/9603111], it has been suggested that there is no Cooper pairing in boson-fermion models of superconductivity. We show that this conjecture is based on an inconsistent approximation that violates an exact identity. Quite generally, the divergence of the fermion t-matrix (the Thouless criterion) is accompanied by the condensation of a boson mode.
LaTeX, 5 pages, 2style files included, 4 embedded EPS figures, submitted to J.Phys.:Condens.Matter