Energies and widths of Efimov states in the three-boson continuum

TL;DR

This paper investigates Efimov states in the three-boson continuum, focusing on their energies and widths as they evolve into resonances, using rigorous scattering equations and exploring universal and finite-range effects.

Contribution

It provides a detailed numerical analysis of Efimov resonances in the continuum, establishing simple parametrizations and examining finite-range influences.

Findings

Resonance energies and widths depend on the two-boson scattering length.

Resonances broaden rapidly and become unobservable as attraction decreases.

Finite-range effects influence the resonance properties.

Abstract

Three-boson Efimov physics is well known in the bound-state regime, but far less in the three-particle continuum at negative two-particle scattering length where Efimov states evolve into resonances. They are studied solving rigorous three-particle scattering equations for transition operators in the momentum space. The dependence of the three-boson resonance energy and width on the two-boson scattering length is studied with several force models. The universal limit is determined numerically considering highly excited states; simple parametrizations for the resonance energy and width in terms of the scattering length are established. Decreasing the attraction, the resonances rise not much above the threshold but broaden rapidly and become physically unobservable, evolving into subthreshold resonances. Finite-range effects are studied and related to those in the bound-state regime.