Double resonances in Borromean heteronuclear triatomic systems

Abstract

We investigate the occurrence of Borromean three-body continuum s-wave resonances, in an $\alpha\alpha\beta$ system for large negative two-body scattering lengths. The energy and width are determined by a scaling function with arguments given by energy ratios of the two-body virtual state subsystem energies with the shallowest three-body bound state. The Borromean continuum resonances emerging from Efimov states present a peculiar behavior for trapped ultracold atoms near a Feshbach resonance: two resonances with equal energies at different values of the scattering length. The corresponding three-body recombination peaks should merge as the temperature is raised, with one moving towards lower values of the scattering length as the other moves to larger values.