Universal Low Energy Features of Two-Body Systems

A. Delfino, T. Frederico, Lauro Tomio

Chen Ji

Few-body systems, such as cold atoms and halo nuclei, share universal features at low energies, which are insensitive to the underlying inter-particle interactions at short ranges. These low-energy properties can be investigated in the framework of effective field theory with two-body and three-body contact interactions. I review the effective-field-theory studies of universal physics in three-body systems, focusing on the application in cold atoms and halo nuclei.

Pascal Naidon, Masahito Ueda

We analyse the recent experiments investigating the low-energy physics of three lithium 6 atoms in three different internal states with resonant two-body scattering lengths. All observed features are qualitatively consistent with the expected Efimov effect, i.e. the effective universal three-body attraction that arises for large values of the scattering lengths. However, we find that a quantitative description at negative energy requires non-universal two- and three-body corrections due to presently unknown behaviour at short distance. An attempt to implement these corrections is made through energy-dependent parameters that are fitted to the experimental data.

Petar Stipanović, Leandra Vranješ Markić, Andrii Gudyma +1 more

Lucas Platter

Lauro Tomio, M. A. Shalchi, Marcelo Takeshi Yamashita +2 more

This contribution reports recent investigations on low-energy scaling properties of three-body systems, by considering elastic s –wave collisions of a particle in a bound-state formed by the remaining two-body system. First, some previous results for the case of the halo nucleus 20 C will be revised, for the neutron– 19 C scattering properties near the critical condition for the occurrence of an excited bound state in 20 C, within a neutron–neutron– 18 C configuration. In our approach, we consider the Faddeev formalism with renormalized zero-range two-body interactions. Next, by considering the actual possibilities for verification of low-energy scaling properties in cold-atom laboratories, the approach is extended to atomic strongly-mass-imbalanced three-body systems, with two identical heavy particles and a light one. In this case, we consider that the heavy particle is being scattered by the light-heavy weakly-bound dimer. Our preliminary results for scattering observable are evidencing the universal scaling features.