Fig. 2

The choices of the contour Γ in Eq. (34), for \({\cal E}\left( k \right) = ck\) (dashed) and \({\cal E}\left( k \right) = k^2/2\mu\) (solid)
The choices of the contour Γ in Eq. (34), for \({\cal E}\left( k \right) = ck\) (dashed) and \({\cal E}\left( k \right) = k^2/2\mu\) (solid)