COOPER INSTABILITY FOR A GIVEN FIELD IN A QUIESCENT FERMI GAS

Citation
Ym. Malozovsky et Jd. Fan, COOPER INSTABILITY FOR A GIVEN FIELD IN A QUIESCENT FERMI GAS, International journal of modern physics b, 12(6), 1998, pp. 637-652
Citations number
31
Categorie Soggetti
Physics, Condensed Matter","Physycs, Mathematical","Physics, Applied
ISSN journal
02179792
Volume
12
Issue
6
Year of publication
1998
Pages
637 - 652
Database
ISI
SICI code
0217-9792(1998)12:6<637:CIFAGF>2.0.ZU;2-4
Abstract
The Cooper instability in a Fermi gas is examined using the perturbati ve diagram approach. A graphical functional derivative technique based on Ward's identity is developed to obtain two-particle interactions a nd then to calculate the vertex part. The pairing instability for a gi ven interaction, such as a phonon (plasmon, etc.) field, occurs in a q uiescent Fermi sea, i.e. without exciting or involving background part icles (holes), only if the interaction is attractive, as first propose d by Cooper and adopted in the BCS (Bardeen-Cooper-Schrieffer) theory. The consequence from this technique provides a way to evaluate the ef fect of the vertex corrections and responses of the Fermi gas in both charge and spin channels incorporating the backward scattering process . The significance of the methodology presented in the present work li es in the fact that it can both reproduce the known results, and, more importantly, be extended to investigate the intermediate or strong co upling case, such as nuclear interactions, where a neglect of vertex c orrections may not be a good approximation.