Generalized Efimov Scenario for Heavy-Light Mixtures

Motivated by recent experimental investigations of Cs-Cs-Li Efimov resonances, this work theoretically investigates the few-body properties of N - 1 noninteracting identical heavy bosons, which interact with a light impurity through a large s-wave scattering length. For Cs-Cs-Cs-Li, we predict the existence of universal four-body states with energies E-4((n,1)) and E-4((n,2)) , which are universally linked to the energy E-3((n)) of the nth Efimov trimer. For infinitely large Cs-133-Li-6 and vanishing Cs-133-Cs-133 scattering lengths, we find (E-4((1,1))/E-3((1)))(1/2) approximate to 1.51 and (E-4((1,2))/E-3((1)))(1/2) approximate to 1.01. The Cs-133-Li-6 scattering lengths at which these states merge with the four-atom threshold, the dependence of these energy ratios on the mass ratio between the heavy and light atoms, and selected aspects of the generalized Efimov scenario for N > 4 are also discussed. Possible implications of our results for ongoing cold atom experiments are presented.