Heteronuclear Efimov scenario with positive intraspecies scattering length

TL;DR

This paper explores heteronuclear Efimov states involving two bosons and one distinguishable particle with positive intraspecies scattering, revealing how the three-body parameter and scaling factor depend on the boson-boson scattering length, with experimental observations of excited Efimov resonances.

Contribution

It provides both theoretical and experimental insights into heteronuclear Efimov physics with positive intraspecies scattering lengths, highlighting the control of Efimov parameters and deviations from universal predictions.

Findings

Observation of two excited Efimov resonances in ultracold Li-Cs mixture.

Measured scaling factor of 4.0(3), deviating from the universal value of 4.9.

Absence of the ground state Efimov resonance in the system.

Abstract

We investigate theoretically and experimentally the heteronuclear Efimov scenario for a three-body system that consists of two bosons and one distinguishable particle with positive intraspecies scattering lengths. The three-body parameter at the three-body scattering threshold and the scaling factor between consecutive Efimov resonances are found to be controlled by the scattering length between the two bosons, approximately independent of short-range physics. We observe two excited-state Efimov resonances in the three-body recombination spectra of an ultracold mixture of fermionic $^6 $Li and bosonic $^{133} $Cs atoms close to a Li-Cs Feshbach resonance, where the Cs-Cs interaction is positive. Deviation of the obtained scaling factor of 4.0(3) from the universal prediction of 4.9 and the absence of the ground state Efimov resonance shed new light on the interpretation of the universality and the discrete scaling behavior of heteronuclear Efimov physics.