Non-Abelian bosonization in a (3+1) -d Kondo semimetal via quantum anomalies

Abstract

Kondo lattice models have established themselves as an ideal platform for studying the interplay between topology and strong correlations such as in topological Kondo insulators or Weyl-Kondo semimetals. The nature of these systems requires the use of nonperturbative techniques, which are few in number, especially in high dimensions. Motivated by this we study a model of Dirac fermions in $(3+1)$ dimensions coupled to an arbitrary array of spins via a generalization of functional non-Abelian bosonization. We show that there exists an exact transformation of the fermions, which allows us to write the system as decoupled free fermions and interacting spins. This decoupling transformation consists of a local chiral, Weyl, and Lorentz transformation parameterized by solutions to a set of nonlinear differential equations, which order by order takes the form of Maxwell's equations with the spins acting as sources. Owing to its chiral and Weyl components this transformation is anomalous and generates a contribution to the action. From this we obtain the effective action for the spins and expressions for the anomalous transport in the system. In the former we find that the coupling to the fermions generates kinetic terms for the spins, a long-ranged interaction, and a Wess-Zumino-like term. In the latter we find generalizations of the chiral magnetic and Hall effects.