Localization of Chiral Electromagnetic Waves on Thick Axion Domain Walls

Nemanja Kaloper

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arXiv · 2606.12513

Localization of Chiral Electromagnetic Waves on Thick Axion Domain Walls

Nemanja Kaloper

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Abstract

We analyze Maxwell theory coupled to an axion domain wall as a spectral boundary value problem. We find that a finite-width axion domain wall generically supports a localized normalizable chiral electromagnetic mode with linear, gapless dispersion. This mode arises from helicity-dependent coupling sourced by the axion gradient: one polarization experiences an effective attractive potential and forms a bound state, while the opposite polarization is repelled. The existence of this chiral surface photon is robust over a wide regime of wall structures and axion masses. Our result shows that axion domain walls generically support a localized chiral photon that has been missed in previous analyses.

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Nemanja Kaloper. 2026-06-10. Localization of Chiral Electromagnetic Waves on Thick Axion Domain Walls. https://arxiv.org/abs/2606.12513

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