Fermions Scattering Off Non-Abelian Rotors

Abstract

We study the dynamics of $d=1+1$ chiral fermions interacting with a rotor impurity. The rotors are non-Abelian, taking values in either an $SU(N)$ group manifold, or an $SU(N)/SO(N)$ coset. At low energies, the fermions pass through the impurity, seemingly unimpeded, but trailing a topological line that is necessary for current conservation. In certain cases, these topological lines exhibit non-Abelian fusion and braiding. This can be viewed as a toy model that captures aspects of s-wave monopole-fermion scattering in $d=3+1$ dimensions.