Pair distribution functions of a superfluid spin-1/2 Fermi gas with contact interactions in the linearized time-dependent BCS theory
We show that the minimal mean-field theory to use for calculating the pair distribution functions $g_{σσ'}(\vec{r},\vec{r}\,')$ of a spatially homogeneous, unpolarized spin-1/2 superfluid Fermi gas is not the ordinary static BCS theory, but the linearized time-dependent BCS theory implemented via the fluctuation-dissipation theorem....