Recombination in the universal four-fermion system

A. Deltuva

doi:10.1016/j.physletb.2021.136599

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arXiv · 2105.09033

Recombination in the universal four-fermion system

A. Deltuva

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Abstract

In the systems of spin $\frac12$ fermions with resonant $S$-wave interactions supporting only weakly bound dimers the antisymmetry forbids recombination of three (or more) fermions at zero energy. However, the fermion-fermion-dimer recombination is only partially suppressed. It is studied in the framework of momentum-space integral equations for the four-particle transition operators. In the vicinity of the unitary limit the fermion-fermion-dimer recombination rate, rescaled to build dimensionless quantity, is found to be linear in the effective range parameter, enabling a simple and accurate parametrization as well as evaluation of finite-range effects for any potential model. This feature makes the present results very useful in benchmarking different methods for three-cluster breakup and recombination calculations in four-particle systems. The interplay of the three-fermion and fermion-fermion-dimer recombination processes and their consequences for ultracold mixtures of fermions and dimers is discussed.

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A. Deltuva. 2021-08-31. Recombination in the universal four-fermion system. https://doi.org/10.1016/j.physletb.2021.136599

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