Three-body recombination in heteronuclear mixtures at finite temperature

Within the universal zero-range theory, we compute the three-body recombination rate to deep molecular states for two identical bosons resonantly interacting with each other and with a third atom of another species, in the absence of weakly bound dimers. The results allow for a quantitative understanding of loss resonances at finite temperature and, combined with experimental data, can be used for testing the Efimov universality and extracting the corresponding three-body parameters in a given system. Curiously, we find that the loss rate can be dramatically enhanced by the resonant heavy-heavy interaction, even for high mass ratios where this interaction is practically irrelevant for the Efimov scaling factor. This effect is important for analyzing the recent loss measurements in the Cs-Li mixture.

Figure 1

Event rate constant $K$ (in units of $\hslash a_{-}^4/m$) versus $a_{-}/a$ for the ${}^6\mathrm{Li}-{}^{87}\mathrm{Rb}-{}^{87}\mathrm{Rb}$ system for various temperatures with the inelasticity parameter set to $\eta =0.2$.

Figure 2

$K$ vs $-1/a_{\mathrm{CsLi}}$ at $T=0$ and $T=400$ nK including and excluding the CsCs interaction. Three-body and inelasticity parameters are set to $R_0=130a_{\mathrm{Bohr}}$ and $\eta =0.6$, respectively.

Figure 3

A three-body wave arriving from large hyper-radii $R$ with amplitude $A_3^{\mathrm{in}}$ in the triatomic channel can follow various pathways before it either returns to large $R$ or gets lost at $R=0$ by turning into an atom and a deep dimer. There is a formal analogy with a Fabry-Perot interferometer with two partially reflecting mirrors.