Speaker: Artem Volosniev

Title: Universal bound states of a few charged particles

Abstract: Few-body bound states whose spatial extent is significantly larger than the range of the binding potential are universal, i.e., their properties are independent of the shape of the underlying interactions. This property drastically simplifies description of important charge-neutral systems, e.g., halo nuclei and Efimov trimers in cold-atom experiments.

This talk is about universal properties of shallow bound states of a few charged particles [1]. The interaction between charges has a short-range attractive part, and a long-range repulsive part given by the Coulomb potential. If the attractive part is deep enough to support a bound state but has a vanishing range, then the corresponding few-body bound states are universal. Their properties are determined by a set of scaling laws; the scales are the Coulomb modified scattering length, the Sommerfeld parameter, and a three-body parameter. Weakly-bound states in finite-range potentials do not obey these scaling laws -- the effective range corrections are important and cannot be neglected, unlike in systems of neutral particles.

[1] C. Schmickler, H.-W. Hammer and A. Volosniev, Phys. Lett. B 798, 135016 (2019).