Dimer-dimer collisions at finite energies in two-component Fermi gases

TL;DR

This paper develops a theoretical framework to accurately analyze four-fermion interactions in two-component Fermi gases, providing finite-energy dimer-dimer scattering parameters crucial for understanding many-body phenomena at finite temperatures.

Contribution

It introduces a generalized technique for the three-body problem applied to four fermions, enabling precise calculation of energy-dependent dimer-dimer scattering properties.

Findings

Finite-energy effects significantly influence dimer interactions.

Dimer dissociation plays a key role in strongly interacting regimes.

Results align with experiments but only partially confirm previous theories.

Abstract

We introduce a major theoretical generalization of existing techniques for handling the three-body problem that accurately describes the interactions among four fermionic atoms. Application to a two-component Fermi gas accurately determines dimer-dimer scattering parameters at finite energies and can give deeper insight into the corresponding many-body phenomena. To account for finite temperature effects, we calculate the energy-dependent complex dimer-dimer scattering length, which includes contributions from elastic and inelastic collisions. Our results indicate that strong finite-energy effects and dimer dissociation are crucial for understanding the physics in the strongly interacting regime for typical experimental conditions. While our results for dimer-dimer relaxation are consistent with experiment, they confirm only partially a previously published theoretical result.