Within the framework of the Lorentz-violating $(3{+}1)$-dimensional extended electrodynamics including the Lorentz-violating CPT-odd Chern-Simons term, we consider the electromagnetic field between two parallel perfectly conducting plates. We find the one-particle eigenstates of such a field, as well as the implicit expression for the photon energy spectrum. In order to find the leading Chern-Simons correction to the vacuum energy, we renormalize and evaluate the sum over all one-particle eigenstate energies using the residue theorem. The resulting correction to the Casimir force, which is attractive and quadratic in the Chern-Simons term, disagrees with the one calculated in [1] and based on wrong equations of motion. Compared with the experimental data, our result places a constraint on the absolute value of the Chern-Simons term.
12.60.Cn Extensions of electroweak gauge sector
11.30.Cp Lorentz and Poincaré invariance
03.65.Pm Relativistic wave equations
Department of Theoretical Physics, Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow, 119991, Russia