# Role of the intraspecies scattering length in the Efimov scenario with large mass difference

## TL;DR

This study investigates how the intraspecies scattering length affects the Efimov scenario in a heteronuclear Cs-Li mixture, combining experiments and multiple theoretical models to understand its influence on three-body loss rates and scaling behavior.

## Contribution

It provides a comprehensive analysis of the intraspecies scattering length's role in heteronuclear Efimov physics using three different theoretical models and experimental data.

## Key findings

- The intraspecies scattering length significantly influences the Efimov scaling behavior.
- Different signs and magnitudes of the intraspecies scattering length lead to distinct three-body loss rate patterns.
- Theoretical models qualitatively agree with experimental observations on the impact of the intraspecies scattering length.

## Abstract

We experimentally and theoretically study the effect of the intraspecies scattering length onto the heteronuclear Efimov scenario, following up on our earlier observation of Efimov resonances in an ultracold Cs-Li mixture for negative [Pires et al., Phys. Rev. Lett. 112, 250404 (2014)] and positive Cs-Cs scattering length [Ulmanis et al., Phys. Rev. Lett. 117, 153201 (2016)]. Three theoretical models of increasing complexity are employed to quantify its influence on the scaling factor and the three-body parameter: a simple Born-Oppenheimer picture, a zero-range theory, and a spinless van der Waals model. These models are compared to Efimov resonances observed in an ultracold mixture of bosonic $^{133}$Cs and fermionic $^6$Li atoms close to two Cs-Li Feshbach resonances located at 843 G and 889 G, characterized by different sign and magnitude of the Cs-Cs interaction. By changing the sign and magnitude of the intraspecies scattering length different scaling behaviors of the three-body loss rate are identified, in qualitative agreement with theoretical predictions. The three-body loss rate is strongly influenced by the intraspecies scattering length.