Renormalization in the Three-body Problem with Resonant P-wave   Interactions
  Resonant P-wave interactions can be described by a minimal zero-range model defined by a truncated effective range expansion, so that the only 2-body interaction parameters are the inverse scattering volume 1/a_P and the P-wave effective range r_P. This minimal model can be formulated as a local quantum field theory with a P-wave interaction between atom fields and a molecular field. In the two-atom sector, the model is renormalizable, but it has unphysical behavior at high energies, because there are negative-probability states with momentum scale r_P. In the sector with three atoms, two of which are identical, renormalization in some parity and angular-momentum channels involves an ultraviolet limit cycle, indicating asymptotic discrete scale invariance. The Efimov effect occurs in the unitary limit a_P^(-1/3), r_P \to 0, but this limit is unphysical because there are low-energy states with negative probability. The minimal model can be of physical relevance only at energies small compared to the energy scale set by r_P, where the effects of negative-probability states are suppressed. 
Eric Braaten, P. Hagen, H.-W. Hammer, and L. Platter
cond-mat.quant-gas hep-ph nucl-th