The electron gas with a strong pairing interaction: Three particle correlations and the Thouless instability

Дата и время публикации : 2000-09-18T13:08:57Z

Авторы публикации и институты :
M. Himmerich
M. Letz

Ссылка на журнал-издание: Phys.Rev.B64:144519,2001
Коментарии к cтатье: 14 pages, 9 figures
Первичная категория: cond-mat.str-el

Все категории : cond-mat.str-el, cond-mat.supr-con

Краткий обзор статьи: We derive simplified Faddeev type equations for the three particle T-matrix which are valid in the Hubbard model where only electrons with opposite spins interact. Using the approximation of dynamical mean field theory these equations are partially solved numerically for the attractive Hubbard model. It is shown that the three particle T-matrix contains a term vanishing $sim T^2$ at the Thouless (or BCS) instability where the two-particle T-matrix diverges. Based on the three particle term we further derive the low density – strong coupling extension for the two-particle vertex function. We therefore understand our equations as a step towards a systematic low density expansion from the weak coupling BCS theory towards the stronger coupling limit.

Category: Physics