文章基本信息

标题：Theoretical Approach to the Gauge Invariant Linear Response Theories for Ultracold Fermi Gases with Pseudogap
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作者：Hao Guo ; Yan He
期刊名称：Advances in Condensed Matter Physics
印刷版ISSN：1687-8108
电子版ISSN：1687-8124
出版年度：2015
卷号：2015
DOI：10.1155/2015/582734
出版社：Hindawi Publishing Corporation
摘要：Recent experimental progress allows for exploring some important physical quantities of ultracold Fermi gases, such as the compressibility, spin susceptibility, viscosity, optical conductivity, and spin diffusivity. Theoretically, these quantities can be evaluated from suitable linear response theories. For BCS superfluid, it has been found that the gauge invariant linear response theories can be fully consistent with some stringent consistency constraints. When the theory is generalized to stronger than BCS regime, one may meet serious difficulties to satisfy the gauge invariance conditions. In this paper, we try to construct density and spin linear response theories which are formally gauge invariant for a Fermi gas undergoing BCS-Bose-Einstein Condensation (BEC) crossover, especially below the superfluid transition temperature . We adapt a particular -matrix approach which is close to the formalism to incorporate noncondensed pairing in the normal state. We explicitly show that the fundamental constraints imposed by the Ward identities and -limit Ward identity are indeed satisfied.