--- res: bibo_abstract: - We study translation-invariant quasi-free states for a system of fermions with two-particle interactions. The associated energy functional is similar to the BCS functional but also includes direct and exchange energies. We show that for suitable short-range interactions, these latter terms only lead to a renormalization of the chemical potential, with the usual properties of the BCS functional left unchanged. Our analysis thus represents a rigorous justification of part of the BCS approximation. We give bounds on the critical temperature below which the system displays superfluidity.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Gerhard foaf_name: Bräunlich, Gerhard foaf_surname: Bräunlich - foaf_Person: foaf_givenName: Christian foaf_name: Hainzl, Christian foaf_surname: Hainzl - foaf_Person: foaf_givenName: Robert foaf_name: Seiringer, Robert foaf_surname: Seiringer foaf_workInfoHomepage: http://www.librecat.org/personId=4AFD0470-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0002-6781-0521 bibo_doi: 10.1142/S0129055X14500123 bibo_issue: '7' bibo_volume: 26 dct_date: 2014^xs_gYear dct_language: eng dct_publisher: World Scientific Publishing@ dct_title: Translation-invariant quasi-free states for fermionic systems and the BCS approximation@ ...