Asymptotic Bound-state Model for Feshbach Resonances

TL;DR

This paper introduces an Asymptotic Bound-state Model that accurately predicts Feshbach resonance positions and widths in two-body systems using minimal parameters, with extensive testing on lithium-potassium and potassium-rubidium systems.

Contribution

The paper presents a novel, analytically based model for Feshbach resonances that simplifies calculations while maintaining accuracy, and demonstrates its effectiveness on real atomic systems.

Findings

Accurately predicts Feshbach resonance positions and widths.

Effective with minimal parameters, using only least bound state energies.

Validated on 6Li-40K and 40K-87Rb systems.

Abstract

We present an Asymptotic Bound-state Model which can be used to accurately describe all Feshbach resonance positions and widths in a two-body system. With this model we determine the coupled bound states of a particular two-body system. The model is based on analytic properties of the two-body Hamiltonian, and on asymptotic properties of uncoupled bound states in the interaction potentials. In its most simple version, the only necessary parameters are the least bound state energies and actual potentials are not used. The complexity of the model can be stepwise increased by introducing threshold effects, multiple vibrational levels and additional potential parameters. The model is extensively tested on the 6Li-40K system and additional calculations on the 40K-87Rb system are presented.