Renormalization group, dimer-dimer scattering, and three-body forces
Boris Krippa, Niels R. Walet, Michael C. Birse
TL;DR
This paper investigates the ratio of fermion-fermion to dimer-dimer scattering lengths in nonrelativistic fermion systems using functional renormalization, highlighting the importance of three-body forces in reducing cutoff dependence.
Contribution
It introduces a three-body term in the renormalization approach, significantly decreasing the cutoff dependence in the scattering length ratio calculation.
Findings
Three-body forces reduce cutoff dependence in the scattering ratio
The ratio between fermion-fermion and dimer-dimer scattering lengths is sensitive to the cutoff
Adding three-body terms improves the robustness of the renormalization results
Abstract
We study the ratio between the fermion-fermion scattering length and the dimer-dimer scattering length for systems of nonrelativistic fermions, using the same functional renormalisation technique as previously applied to fermionic matter. We find a strong dependence on the cutoff function used in the renormalisation flow for a two-body truncation of the action. Adding a simple three-body term substantially reduces this dependence.
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