Ultracold atoms have recently emerged as an efficient platform to study fundamental processes in few-body systems. The short-range character of the van der Waals interatomic interaction potential allows for a single parameter to describe the scattering processes at low energies: the s-wave scattering length. The latter parameter, defining the strength and the sign of the interactions, can be tuned to any value by means of an external magnetic field, rendering the possibility to investigate the whole range of interactions - from vanishingly weak to resonantly strong.

In my talk I shall overview our experimental studies of the three-body recombination process in a gas of ultracold lithium atoms. In the regime of resonant interactions we identify the characteristic features of Efimov physics, i.e. the physics of extremely large and weakly bound universal trimers. The properties of these states are usually described by the s-wave scattering length and the so-called three-body parameter which is dominated by the van der Waals length, as was shown recently. In the opposite regime of vanishingly weak interactions, where no universal bound states are expected, we discover a surprisingly simple behavior. We show that only going to the second term in the collisional phase effective range expansion is sufficient to describe the rate of the recombination processes. We, thus, predict the behavior of the dominant mechanism of atom loss from traps, caused by the three-body recombination, in the whole range of interatomic interactions.  This knowledge, apart from being of fundamental interest, can be used in optimization of evaporative cooling to reach a Bose-Einstein condensate phase and in optimization of its lifetime.