Renyuan Liao and Khandker F. Quader, Medium effects close to s- and p-wave Feshbach resonances in atomic Fermi gases, Physical Review A 86(1), 012704 (2012).
摘要：Many-body effects may influence properties, such as scattering parameters, nature of pairing, etc., close to a Feshbach resonance in the fermion BEC-BCS crossover problem. We study effects such as these using a tractable crossing-symmetric approach. This method allow us to include quantum fluctuations, such as density, current, spin, spin-current, and the higher-order fluctuations in a self-consistent fashion. The underlying fermion interaction is reflected in the “driving” term. We perform calculations here on both Bose-Einstein condensate (BEC) and BCS sides and taking the driving term to be finite range and of arbitrary strength. These are related to two-body singlet and triplet scattering parameters and can be connected with experimental s- and p-wave Feshbach resonances. We include the ℓ=0 density and spin fluctuations as well as ℓ=1 current and spin-current fluctuations. We calculate renormalized scattering amplitudes, pairing amplitudes, nature of pairing, etc., on both the BEC and BCS sides. We then compare our results qualitatively with experiments.
Renyuan Liao, Zhi-Gao Huang, Wei-feng Yang, Wu-Ming Liu, Thermal-assisted anisotropy and anisotropy-driven instability in the superfluid state of two-species fermionic polar molecules, Physics Letters A 376(26-27), 1986-1991 (2012).
摘要：We study the superfluid state of two-species heteronuclear Fermi gases with isotropic contact and anisotropic long-range dipolar interactions. We find that the temperature tends to increase the anisotropy of the pairing state, which is rather counterintuitive. We study the anisotropic properties of the system by examining the angular dependence of the number density distribution, the excitation spectrum and the pair correlation function. The competing effects of the contact interaction and the dipolar interaction upon the anisotropy are revealed. We derive and compute the superfluid mass density ρij for the system.
