Three-body loss in lithium from functional renormalization
  We use functional integral methods for an estimate of the three-body loss in a three-component $^6$Li ultracold atom gas. We advocate a simple picture where the loss proceeds by the formation of a three-atom bound state, the trion. In turn, the effective amplitude for the trion formation from three atoms is estimated from a simple effective boson exchange process. The energy gap of the trion and other key quantities for the loss coefficient are computed in a functional renormalization group framework. 
R. Schmidt, S. Floerchinger, and C. Wetterich