Trimer and Tetramer Bound States in Heteronuclear Systems

TL;DR

This paper investigates bound states in heteronuclear systems with two or three heavy bosons and another atom, using variational and integral equation methods to explore Efimov physics near the dimer threshold.

Contribution

It provides new calculations of heteronuclear Efimov states on the positive scattering length side, complementing previous studies at the unitary limit and breakup threshold.

Findings

Identification of trimer and tetramer bound states in heteronuclear systems.

Calculation of Efimov scaling behavior near the dimer threshold.

Extension of previous models to positive scattering lengths.

Abstract

The Efimov effect in heteronuclear cold atomic systems is experimentally more easily accessible than the Efimov effect for identical atoms, because of the potentially smaller scaling factor. We focus on the case of two or three heavy identical bosons and another atom. The former case was recently observed in a mixture of 133Cs and 6Li atoms. We employ the Gaussian Expansion Method as developed by Hiyama, Kino et al.. This is a variational method that uses Gaussians that are distributed geometrically over a chosen range. Supplemental calculations are performed using the Skorniakov-Ter-Martirosian equation. Blume et al. previously investigated the scaling properties of heteronuclear systems in the unitary limit and at the three-body breakup threshold. We have completed this picture by calculating the behaviour on the positive scattering length side of the Efimov plot, focussing on the dimer threshold.