Axion electrodynamics and nonrelativistic photons in nuclear and quark matter

TL;DR

This paper demonstrates that in dense nuclear and quark matter, electromagnetic fields behave according to axion electrodynamics, leading to nonrelativistic gapless photon modes that could also appear at topological insulator interfaces.

Contribution

It introduces the concept of nonrelativistic photons in nuclear and quark matter via axion electrodynamics, linking high-energy physics with condensed matter phenomena.

Findings

One helicity state of photons exhibits a nonrelativistic gapless dispersion relation.

The other photon helicity state is gapped.

Nonrelativistic photons may also occur at topological insulator interfaces.

Abstract

We argue that the effective theory for electromagnetic fields in spatially varying meson condensations in dense nuclear and quark matter is given by the axion electrodynamics. We show that one of the helicity states of photons there has the nonrelativistic gapless dispersion relation $\omega \sim k^2$ at small momentum, while the other is gapped. This "nonrelativistic photon" may also be realized at the interface between topological and trivial insulators in condensed matter systems.