Weakly bound cluster states of Efimov character

We study the behaviour of weakly bound clusters and their relation to the well-known three-body Efimov states. We adopt a model to describe the universal behaviour of strongly interacting bosonic systems, and we test its validity by reproducing predictions of three- and four-body universal states. Then, we extend our study to larger systems and identify a series of universal cluster states that can be qualitatively interpreted as adding one particle at a time to an Efimov trimer. The properties of these cluster states and their experimental signatures are discussed.