Investigation of Efimov Features and Universality in $^{87}$Rb-$^{40}$K Mixtures with finite-range interaction

TL;DR

This paper investigates Efimov features in $^{87}$Rb-$^{40}$K mixtures, revealing finite-range effects and predicting new resonances, thereby testing the universality of Efimov physics beyond zero-range approximations.

Contribution

It introduces a finite-range model using the Lennard-Jones potential to analyze Efimov features in heteronuclear mixtures, highlighting effects overlooked by zero-range theories.

Findings

Prediction of three-body shape resonances at large negative scattering lengths

Identification of an Efimov recombination minimum beyond previous measurements

Demonstration of finite-range effects influencing Efimov universality

Abstract

The study of Efimov features and their relationships in $^{40}$K-$^{87}$Rb Mixtures has generated extensive discussion, yet the discrepancy between Efimov universality predictions based on the zero-range approximation and experimental observations remains unresolved. In this study, we investigate the three-body collision properties with $J=0$ symmetry for a $^{87}$Rb-$^{87}$Rb-$^{40}$K system on both sides of Rb-K scattering length to understand the mechanisms underlying this discrepancy. Our approach employs the R-matrix propagation method within a hyperspherical coordinate frame, utilizing the Lennard-Jones model potential to describe atom interactions. We predicts the existence of three-body shape resonances at large negative Rb-K scattering lengths, which leads to the enhancement of three-body recombination rates. On the positive Rb-K scattering length side, we find an Efimov recombination minimum beyond the range of previous measurements. These Efimov features, combined with experimental observations of the atom-dimer Efimov resonance, offer an opportunity to test the universality of Efimov features. Our study demonstrates the influence of finite-range effects and non-resonant intraspecies scattering length in $^{40}$K-$^{87}$Rb mixtures, providing valuable insights into the universal relations between Efimov features in heteronuclear systems.