Anomalous Casimir effect in axion electrodynamics

Abstract

We study the Casimir effect in axion electrodynamics. A finite $\hat{I}¸$-term affects the energy dispersion relation of photon if $\hat{I}¸$ is time and/or space dependent. We focus on a special case with linearly inhomogeneous $\hat{I}¸$ along the $z$-axis. Then we demonstrate that the Casimir force between two parallel plates perpendicular to the $z$-axis can be either attractive or repulsive, dependent on the gradient of $\hat{I}¸$. We call this repulsive component in the Casimir force induced by inhomogeneous $\hat{I}¸$ the anomalous Casimir effect.

8 pages, 2 figures; typos in Eqs.(30) and (A6) fixed; results unchanged; accepted in PRD