Three-body recombination near the d-wave resonance in ultracold $^{85}$Rb\,-$^{87}$Rb mixtures

TL;DR

This study investigates three-body recombination rates near the d-wave Feshbach resonance in ultracold $^{85}$Rb-$^{87}$Rb mixtures, revealing mechanisms of enhancement and the influence of intraspecies interactions.

Contribution

It provides a detailed analysis of recombination mechanisms near the d-wave resonance, highlighting the role of intraspecies interactions and the effects of different scattering length regimes.

Findings

Recombination enhancement occurs via shape resonance on positive scattering length side.

Coupling between entrance and recombination channels causes enhancement on negative side.

Intraspecies interactions significantly influence the emergence of recombination rate enhancements.

Abstract

We have studied the three-body recombination rates on both sides of the interspecies d-wave Feshbach resonance in the $^{85}$Rb\,-$^{87}$Rb-$^{87}$Rb system using the $R$-matrix propagation method in the hyperspherical coordinate frame. Two different mechanisms of recombination rate enhancement for positive and negative $^{85}$Rb\,-$^{87}$Rb d-wave scattering lengths are analyzed. On the positive scattering length side, the recombination rate enhancement occurs due to the existence of three-body shape resonance, while on the negative scattering length side, the coupling between the lowest entrance channel and the highest recombination channel is crucial to the appearance of the enhancement. In addition, our study shows that the intraspecies interaction plays a significant role in determining the emergence of recombination rate enhancements. Compared to the case in which the three pairwise interactions are all in d-wave resonance, when the $^{87}$Rb-$^{87}$Rb interaction is near the d-wave resonance, the values of the interspecies scattering length that produce the recombination enhancement shift. In particular, when the $^{87}$Rb-$^{87}$Rb interaction is away from the d-wave resonance, the enhancement disappears on the negative interspecies scattering length side.