Effective interaction between molecules in the BEC regime of a superfluid Fermi gas

Abstract

We investigate the effective interaction between Cooper-pair molecules in the st rong-coupling BEC regime of a superfluid Fermi gas with a Feshbach resonance. Our work uses a path integral formulation and a renormalization group (RG) analy sis of fluctuations in a single-channel model. We show that a physical cutoff en ergy ${\omega }_c$ originating from the finite molecular binding energy is the key to understanding the interaction between molecules in the BEC regime. Our work t hus clarifies recent results by showing that $a_{\mathrm{M}}=2a_{\mathrm{F}}$ is a {\it ba re} molecular scattering length while $a_{\mathrm{M}}=(0.6\sim 0.75)a_{\mathrm{F}}$ is the low energy molecular scattering length renormalized to include high-energy scat tering up to ${\omega }_c$ (here $a_{\mathrm{F}}$ is the scattering length between Fermi atoms). We also include many-body effects at finite temperatures. We find that $a_{\mathrm{M}}$ is strongly dependent on temperature, vanishing at $T_{\mathrm{c}}$, consistent with the earlier Bose gas results of Bijlsma and Stoof.

arXiv comment10 pages, 3 figures

References in corpus (10)

• Crossover from a molecular Bose-Einstein condensate to a degenerate Fermi gas
• Weakly bound dimers of fermionic atoms
• Equation of state of a Fermi gas in the BEC-BCS crossover: a quantum Monte Carlo study
• Resonance superfluidity in a quantum degenerate Fermi gas
• The BCS-BEC Crossover in a Gas of Fermi Atoms with a Feshbach Resonance
• Prospect of creating a composite fermi/bose superfluid
• The transition temperature of the dilute interacting Bose gas
• On the correct strong-coupling limit in the evolution from BCS superconductivity to Bose-Einstein condensation
• Critical Temperature of Bose-Einstein Condensation of Hard Sphere Gases
• Renormalization Group Theory of the Three-Dimensional Dilute Bose Gas

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• Dynamical instability of a driven-dissipative electron-hole condensate in the BCS-BEC-crossover region
• Critical Behaviour in Trapped Strongly Interacting Fermi Gases
• Strong-coupling corrections to spin susceptibility in the BCS-BEC crossover regime of a superfluid Fermi gas
• Spin-polarized Fermi superfluids as Bose-Fermi mixtures
• Pairing fluctuations and anisotropic pseudogap phenomenon in an ultracold superfluid Fermi gas with plural $p$-wave superfluid phases
• Role of the effective range in the density-induced BEC-BCS crossover
• Effective field theory of boson-fermion mixtures and bound fermion states on a vortex of boson superfluid
• Isothermal compressibility and effects of multi-body molecular interactions in a strongly interacting ultracold Fermi gas