Full-dimensional quantum mechanical study of three-body recombination for cold ⁴He-⁴He-²⁰Ne system

The increase of the number of the two-body recombination channels strongly challenges the numerical calculation of the accurate rates for the three-body recombination (TBR) process and its reverse process, collision-induced dissociation (CID), at ultracold temperatures. By taking the ⁴He-⁴He-²⁰Ne collision system as an example, we have obtained the rates for its TBR and CID processes involving all four recombination channels, including the two-body states ⁴He₂ (l = 0) and ⁴He²⁰Ne (l = 0, 1, 2) with l the rotational quantum number. By using the adiabatic hyperspherical method, we have considered not only total angular momentum J = 0 but also J > 0 in the ultracold collision energies (E = 0.01 - 100 mK × k_B). It is found that ⁴He₂ (l = 0) is the major product after the TBR process in the ultracold limit (E ≤ 0.1 mK × k_B). The TBR rate into ⁴He₂ (l = 0) is nearly one order of magnitude larger than the sum of the other three products, ⁴He²⁰Ne (l = 0, 1, 2). Moreover, the CID rates for the three ⁴He²⁰Ne (l = 0, 1, 2) + ⁴He initial states are close to each other and are smaller than that for the ⁴He₂ (l = 0) + ²⁰Ne initial state. Additionally, we have, for the first time, performed the channel-resolved scattering calculation that can explain the above-mentioned findings quantitatively.