Three-Body Recombination of Ultracold Atoms to a Weakly Bound s Level.

We discuss three-body recombination of ultracold atoms to a weakly bound {ital s} level. In this case, characterized by large and positive scattering length {ital a} for pair interaction, we find a repulsive effective potential for three-body collisions, which strongly reduces the recombination probability. In the zero temperature limit we obtain a universal relation, independent of the detailed shape of the interaction potential, for the (event) rate constant of three-body recombination: {alpha}{sub rec}=3.9 {h_bar}{ital a}{sup 4}/{ital m}, where {ital m} is the atom mass. {copyright} {ital 1996 The American Physical Society.}