Universal 1+2-body bound states in planar atomic wave guides

Shallow heteronuclear trimers are predicted for mixtures of two atomic species strongly trapped in a quasi two-dimensional atomic wave guide. The binding energies are functions of the 2D-scattering length and of the mass ratio and can be thus tuned by various ways. These universal trimers are composed of two identical non interacting particles and of a third particle of the other species. Depending on the statistics of the two identical particles, the trimers have an odd (fermions) or even (bosons) internal angular momentum. These results permit to draw conclusions on the stability issue for the quasi-2D gaseous phase of heteronuclear dimers.