Recombination in the universal four-fermion system

Abstract

In the systems of spin $\frac{1}{2}$ 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.

modified definition of the recombination rate

References in corpus (7)

• Weakly bound dimers of fermionic atoms
• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Energetics and Structural Properties of Trapped Two-Component Fermi Gases
• Neutron-${}^3$H scattering above the four-nucleon breakup threshold
• Dimer-dimer collisions at finite energies in two-component Fermi gases
• Universal dimer-dimer scattering in lattice effective field theory
• Universality in fermionic dimer-dimer scattering