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One-electron spectral functions of the attractive Hubbard model for intermediate coupling

1998; American Physical Society; Volume: 57; Issue: 10 Linguagem: Inglês

10.1103/physrevb.57.5995

1095-3795

M. Yu. Kagan, Raymond Frésard, Massimiliano Capezzali, H. P. Beck,

Advanced Chemical Physics Studies

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.