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arXiv · 2608.22177

Plasmon-polaritons in a rarefied nonrelativistic neutron gas

P. O. Kazinski·A. M. Trushchuk
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Abstract

The electromagnetic properties of a dilute unpolarized nonrelativistic neutron gas are described in the case when neutron-by-neutron scattering is negligible. The Gaussian (Maxwell-Boltzmann) and Fermi-Dirac one-particle density matrices for the neutron gas are considered, the typical space scale of variations of these density matrices being assumed to be much larger than the the typical space scale of variations of the electromagnetic field. The Green functions for the static effective Maxwell equations are obtained. The parameters of a nonequilibrium neutron gas are found where this gas possesses a ferromagnetic instability. The analog of Friedel oscillations is described. The properties of plasmon-polaritons in the neutron gas are revealed. It turns out that the dispersion law of longitudinal and transverse plasmon-polaritons has an infinite number of branches at a given momentum. The region of parameters where the plasmon-polaritons can be regarded as quasiparticles is found. The plasmon-polaritons on a Gaussian wave packet of a single electron are described. Their dispersion law proves to have an infinite number of branches at a given momentum. It is shown that there exist stable longitudinal plasmon-polaritons even on a single electron.

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P. O. Kazinski, A. M. Trushchuk. 2026-08-23. Plasmon-polaritons in a rarefied nonrelativistic neutron gas. https://arxiv.org/abs/2608.22177

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