Convergence of a renormalization group approach to dimer-dimer scattering

TL;DR

This paper investigates the convergence of a functional renormalisation group method in calculating dimer-dimer scattering lengths in nonrelativistic fermion systems, demonstrating rapid convergence and agreement with exact results.

Contribution

It shows that a systematic expansion in the functional renormalisation group approach rapidly converges and accurately predicts the ratio of fermion-fermion to dimer-dimer scattering lengths.

Findings

Rapid convergence of the renormalisation group results.

Agreement with known exact results.

Effective method for studying fermionic scattering lengths.

Abstract

We study the convergence of a functional renormalisation group technique by looking at the ratio between the fermion-fermion scattering length and the dimer-dimer scattering length for a system of nonrelativistic fermions. We find that in a systematic expansion in powers of the fields there is a rapid convergence of the result that agrees with know exact results.