The study of few-particle systems in the limit of large two-body scattering length is an intense subject of research nowadays. In this limit, particle systems show universal behavior largely independent of the range and characteristics of the particular interaction. Research on universal behavior in few-body systems has been triggered by the seminal work of Efimov who demonstrated that in the unitary limit, that means infinite scattering length, the three-boson system has an infinite number of excited states that accumulate to zero following a geometrical series. As the scattering length moves from the unitary limit to finite values, the infinite tower of energy levels become finite tending to the natural distribution of levels observed in most real systems. The very peculiar energy spectrum of a three-boson system at the
unitary limit is called Efimov effect and the study of the dynamics of that system close to the unitary limit is called Efimov physics.
In this talk, I give an introduction to Efimov physics and I show how the universality of the three-body systems spreads to the other few-body sectors.