The past decade developments of condensed matter physics research have put a great weight in the importance of topological phenomena. Starting with topological insulators and superconductors new concepts and phase emerged; our particular interest here are Weyl semi-metals. Differently from its insulating and superconducting topological cousins, the low-energy physics of Weyl semi-metals is not restricted to its surface, with electronic properties being governed by linearly dispersing bulk bands. An effective Lorentz symmetry thus comes about in these materials, settling Weyl semi-metals as prime candidates to study comparative and analogue high-energy physics. In this context, we will consider the particular phenomenon of the chiral anomaly, which in high-energy physics controls the decay rates of neutral pions into photons. This phenomenon is traditionally understood in condensed matter as giving rise to novel electronic transport phenomenology, whose verification, however, has been seen with controversy in the literature. To avoid such controversies, we take a different approach, showing that optical properties of lattice oscillations carry singular signatures of the chiral anomaly. This comes about by means of a novel type of polariton effect and is restricted only to certain classes of lattice oscillations in mirror symmetry broken Weyl semi-metals. Our proposed signatures are then robust, and provide clear constrains in the systems to be studied, helping guide experimental efforts.

P. Rinkel, __P. L. S. Lopes__, I. Garate