Looking for "avalanche-mechanism" loss at an atom-molecule Efimov resonance

TL;DR

This study investigates the presence of avalanche-mechanism related atom loss features at an Efimov resonance in ultracold 40K-87Rb gases, finding no experimental evidence supporting the theoretical predictions of such features.

Contribution

The paper provides the first experimental search for avalanche-mechanism loss features at a known atom-molecule Efimov resonance in a mixed atomic gas.

Findings

No broad atom loss feature observed near the Efimov resonance.

Experimental results are inconsistent with existing avalanche mechanism theories.

Monte Carlo simulations also failed to reproduce narrow loss features.

Abstract

The "avalanche mechanism" has been used to relate Efimov trimer states to certain enhanced atom loss features observed in ultracold atom gas experiments. These atom loss features are argued to be a signature of resonant atom-molecule scattering that occurs when an Efimov trimer is degenerate with the atom-molecule scattering threshold. However, observation of these atom loss features has yet to be combined with the direct observation of atom-molecule resonant scattering for any particular atomic species. In addition, recent Monte-Carlo simulations were unable to reproduce a narrow loss feature. We experimentally search for enhanced atom loss features near an established scattering resonance between 40K87Rb Feshbach molecules and 87Rb atoms. Our measurements of both the three-body recombination rate in a gas of 40K and 87Rb atoms and the ratio of the number loss for the two species do not show any broad loss feature and are therefore inconsistent with theoretical predictions that use the avalanche mechanism.