Universal properties and structure of halo nuclei

TL;DR

This paper explores the universal properties and structure of two-neutron halo nuclei using an effective quantum mechanics approach, identifying potential Efimov states and analyzing structural characteristics like radii and form factors.

Contribution

It introduces an effective three-body model for halo nuclei, quantifies uncertainties, and assesses the possibility of observing Efimov states in 20C based on experimental data.

Findings

20C may host an Efimov excited state less than 7 keV below threshold

Calculated matter form factors and radii for 2n halo nuclei

Estimated two-neutron opening angles in halo nuclei

Abstract

The universal properties and structure of halo nuclei composed of two neutrons (2n) and a core are investigated within an effective quantum mechanics framework. We construct an effective interaction potential that exploits the separation of scales in halo nuclei and treat the nucleus as an effective three-body system. The uncertainty from higher orders in the expansion is quantified through theoretical error bands. First, we investigate the possibility to observe excited Efimov states in 2n halo nuclei. Based on the experimental data, 20C is the only halo nucleus candidate to possibly have an Efimov excited state, with an energy less than 7 keV below the scattering threshold. Second, we study the structure of 20C and other 2n halo nuclei. In particular, we calculate their matter form factors, radii, and two-neutron opening angles.