The 3-body recombination rate at threshold for distinguishable atoms withlarge negative pair scattering lengths is calculated in the zero-rangeapproximation. The only parameters in this limit are the 3 scattering lengthsand the Efimov parameter, which can be complex valued. We provide semi-analyticexpressions for the cases of 2 or 3 equal scattering lengths and we obtainnumerical results for the general case of 3 different scattering lengths. Ourgeneral result is applied to the three lowest hyperfine states of Lithium-6atoms. Comparisons with recent experiments provide indications of loss featuresassociated with Efimov trimers near the 3-atom threshold.
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