paper

Precursor of Superfluidity in a Strongly Interacting Fermi Gas with Negative Effective Range

arXiv:1802.00919 · doi:10.1103/PhysRevA.97.043613

Abstract

We theoretically investigate the effects of pairing fluctuations in an ultracold Fermi gas near a Feshbach resonance with a negative effective range. By employing a many-body T-matrix theory with a coupled boson-fermion model, we show that the single-particle density of states exhibits the so-called pseudogap phenomenon which is a precursor of superfluidity induced by strong pairing fluctuations. We clarify the region where strong pairing fluctuations play a crucial role in single-particle properties, from the broad-resonance region to the narrow-resonance limit at the divergent two-body scattering length. We also extrapolate the effects of pairing fluctuations to the positive-effective-range region from our results near the narrow Feshbach resonance. Results shown in this paper are relevant to the connection between ultracold Fermi gases and low-density neutron matter from the viewpoint of finite-effective-range corrections.

21 pages, 8 figures

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