[1104.2387] Liberating Efimov physics from three dimensions

[1104.2387] Liberating Efimov physics from three dimensions: When two particles attract via a resonant short-range interaction, three particles always form an infinite tower of bound states characterized by a discrete scaling symmetry. It has been considered that this Efimov effect exists only in three dimensions. Here we review how the Efimov physics can be liberated from three dimensions by considering two-body and three-body interactions in mixed dimensions and four-body interaction in one dimension. In such new systems, intriguing phenomena appear, such as confinement-induced Efimov effect, Bose-Fermi crossover in Efimov spectrum, and formation of interlayer Efimov trimers, and will be observable in ultracold atom experiments. This study significantly broadens our horizons of universal Efimov physics.