Fate of the neutron-deuteron virtual state as an Efimov level

TL;DR

This paper investigates the theoretical emergence of Efimov states in three-body nuclear systems near unitarity, showing that virtual states can evolve into shallow bound states, with results applicable beyond the specific system studied.

Contribution

It provides a model-independent effective field theory analysis demonstrating the universal emergence of Efimov levels in three-body systems near unitarity.

Findings

Virtual states evolve into shallow bound states near unitarity

Efimov levels are not directly observed in the three-nucleon system

Results are universal and applicable beyond the specific system studied

Abstract

The emergence of Efimov levels in a three-body system is investigated near the unitarity limit characterized by resonating two-body interaction. No direct evidence of Efimov levels is seen in the three-nucleon system since the triton is the only physical bound state. We provide a model-independent analysis of nucleon-deuteron scattering at low energy by formulating a consistent effective field theory. We show that virtual states evolve into shallow bound states, which emerge as excited triton levels as we drive the system towards unitarity. Even though we consider this specific system, our results for the emergence of the Efimov levels are universal.