Fermi gas throughout the BCS-BEC crossover: Comparative study of t-matrix approaches with various degrees of self-consistency
Anno: 2019
Autori: Pini M., Pieri P., Strinati Calvanese G.
Affiliazione autori: School of Science and Technology, Physics Division, Universita di Camerino, Camerino (MC), 62032, Italy; INFN, Sezione di Perugia, Perugia (PG), 06123, Italy; CNR-INO, Istituto Nazionale di Ottica, Sede di Firenze, Firenze (FI), 50125, Italy
Abstract: The diagrammatic t-matrix approximation has often been adopted to describe a dilute Fermi gas. This approximation, originally considered by V. M. Galitskii (Zh. Eksp. Teor. Fiz. 34, 151 (1958) [Sov. Phys. JETP 7, 104 (1958)]) for a repulsive interparticle interaction, was later widely utilized for an attractive Fermi gas to describe the BCS-BEC crossover from strongly overlapping Cooper pairs in weak coupling to nonoverlapping composite bosons in strong coupling. Several variants of the t-matrix approximation have been considered in the literature, which are distinguished by the degree of self-consistency allowed in the building blocks of the diagrammatic structure. Here, we perform a systematic and comparative study of all possible variants on the degree of self-consistency for the t-matrix approximation in an attractive Fermi gas, which enables us to confront their outcomes for thermodynamic and dynamical quantities on the same footing in an unbiased way. For definiteness, only the normal phase above the superfluid critical temperature is considered. The dispute that can be raised in this context, about the adequateness of introducing progressive degrees of self-consistency over and above the non-self-consistent t-matrix approximation for an attractive Fermi gas, parallels the recent interest in the literature in assessing the importance of various degrees of self-consistency in the context of semiconductors and insulators
Giornale/Rivista: PHYSICAL REVIEW B
Volume: 99 (9) Da Pagina: 094502-1 A: 094502-19
Maggiori informazioni: M.P. acknowledges L. Fallani for support and discussions. This work was partially supported by the Italian MIUR under Contract PRIN-2015 No. 2015C5SEJJ001.Parole chiavi: SUPERCONDUCTIVITY; APPROXIMATIONS; CONDENSATION; CONVERGENCEDOI: 10.1103/PhysRevB.99.094502Citazioni: 28dati da “WEB OF SCIENCE” (of Thomson Reuters) aggiornati al: 2024-04-14Riferimenti tratti da Isi Web of Knowledge: (solo abbonati) Link per visualizzare la scheda su IsiWeb: Clicca quiLink per visualizzare la citazioni su IsiWeb: Clicca qui