Casimir effect in dense QCD matter

The conventional Casimir effect is defined for photon fields, whereas various quasiparticle fields realized in condensed matter systems can lead to novel types of Casimir-effect-like phenomena [e.g., arXiv:2207.14078]. In QCD and nuclear physics, such a situation is rare, but there are some possibilities in dense QCD/nuclear matter. For example, the chiral density wave phase and the chiral soliton lattice phase are expected to be the ground states of finite-density QCD in a zero and a strong magnetic field, respectively. In this talk, we discuss the typical features of the Casimir effect in a small-size medium composed of such ground states. For example, the fermionic Casimir effect in the chiral density wave phase leads to oscillations of physical quantities as a function of system size. Also, the photonic Casimir effect is described based on the so-called axion electrodynamics, and anomalous behaviors of the Casimir effect can occur.