Consequences of a condensed matter realization of Lorentz violating QED in Weyl semi-metals

TL;DR

This paper explores how Weyl semi-metals serve as a condensed matter realization of Lorentz violating QED, resolving theoretical ambiguities and predicting observable effects like birefringence.

Contribution

It demonstrates that the ambiguity in the Chern-Simons term in Lorentz violating QED is resolved in Weyl semi-metals due to a microscopic model, and discusses observable consequences.

Findings

Ambiguity in the Chern-Simons term is absent in Weyl semi-metals.

A full microscopic model underpins the effective theory.

Observable birefringence effects are predicted.

Abstract

In Lorentz violating quantum electrodynamics (QED) it is known that a radiatively induced Chern-Simons term appears in the effective action for the gauge field, which is finite but undetermined. This ambiguity is shown to be absent in a condensed matter realization of such a theory in Weyl semi-metals due to the existence of a full microscopic model from which this effective theory emerges. Physically observable consequences such as birefringence are also discussed in this scenario.