We calculate the one-electron spectral function of the attractive
(negative-U) Hubbard model. We work in the intermediate coupling and low
density regime and obtain the self-energy in an approximate analytical form.
The excitation spectrum is found to consist of three branches. The results are
obtained in a framework, based on the self-consistent T-matrix approximation,
which is compatible with the Mermin-Wagner theorem.Comment: 7 pages, revtex, 7 figures in postscript format, submitted to PR
