Premium
1/N expansions for the U = ∞ Hubbard model: Comparison between X‐operator and slave‐boson approach
Author(s) -
Gehlhoff L.
Publication year - 1996
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221970217
Subject(s) - hubbard model , degeneracy (biology) , operator (biology) , boson , mathematical physics , t j model , physics , order (exchange) , mathematics , quantum mechanics , economics , biochemistry , chemistry , superconductivity , repressor , gene , transcription factor , biology , finance , bioinformatics
We consider the large‐spin‐degeneracy (N) version of the U = ∞ one‐band Hubbard model and present a systematic 1/N expansion method which is based on Hubbard's X‐operator formulation and a Baym‐Kadanoff expansion. We compare this alternative X‐operator approach with the customary time‐continuum slave‐boson (SB) functional‐integral treatment, which has recently been criticized. In particular, we give a detailed derivation of the density Green's function within the new approach and compare the leading‐order results with those as obtained with the commonly used SB treatment, finding total agreement.