We study three- and four-body Efimov physics in a heteronuclear atomic system
with three identical heavy bosonic atoms and one light atom. We show that
exchange of the light atom between the heavy atoms leads to both three- and
four-body features in the low-energy inelastic rate constants that trace to the
Efimov effect. Further, the effective interaction generated by this exchange
can provide an additional mechanism for control in ultracold experiments.
Finally, we find that there is no true four-body Efimov effect - that is, no
infinite number of four-body states in the absence of two- and three-body bound
states - resolving a decades-long controversy.Comment: 5 pages, 4 figure
