# Few-body physics in resonantly interacting ultracold quantum gases

## TL;DR

This paper reviews the role of Efimov physics in ultracold quantum gases, presenting a universal classification of three-body interactions and analyzing their impact on scattering processes and stability.

## Contribution

It introduces a universal classification scheme for three-body systems using hyperspherical representation, clarifying their bound and scattering properties in ultracold gases.

## Key findings

- Efimov physics significantly influences three-body scattering processes.
- Universal classification simplifies understanding of three-body interactions.
- Insights into stability and lifetime of ultracold gases are provided.

## Abstract

We provide a general discussion on the importance of three-body Efimov physics for strongly interacting ultracold quantum gases. Using the adiabatic hyperspherical representation, we discuss a universal classification of three-body systems in terms of the attractive or repulsive character of the effective interactions. The hyperspherical representation leads to a simple and conceptually clear picture for the bound and scattering properties of three-body systems with strong $s$-wave interactions. Using our universal classification scheme, we present a detailed discussion of all relevant ultracold three-body scattering processes using a pathway analysis that makes evident the importance of Efimov physics in determining the energy and scattering length dependence of such processes. This article provides a general overview of the current status of the field and a discussion of various issues relevant to the lifetime and stability of ultracold quantum gases along with universal properties of ultracold, resonantly interacting, few-body systems.