Medium effects close to s- and p-wave Feshbach resonances in atomic Fermi gases

TL;DR

This paper investigates many-body effects near s- and p-wave Feshbach resonances in atomic Fermi gases using a crossing-symmetric approach that includes quantum fluctuations, providing insights into scattering, pairing, and experimental comparisons.

Contribution

It introduces a self-consistent method to include quantum fluctuations in Fermi gases near Feshbach resonances, connecting theoretical scattering parameters with experimental observations.

Findings

Calculated renormalized scattering amplitudes and pairing properties.

Analyzed effects of density, spin, current, and spin-current fluctuations.

Compared theoretical results qualitatively with experimental data.

Abstract

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 $\ell=0$ density and spin fluctuations, as well as $\ell=1$ 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.