# [2011.07465] Radiation of twisted photons from charged particles moving in cholestericsopen searchopen navigation menucontact arXivsubscribe to arXiv mailings

The radiation of twisted photons by charged particles traversing a cholesteric plate is studied in the framework of quantum electrodynamics in an anisotropic inhomogeneous dispersive medium. The complete set of solutions to the Maxwell equations in the cholesteric plate is constructed in the paraxial and small anisotropy approximations. The explicit expressions for the average numbers of plane-wave and twisted photons created by a charged point particle crossing the cholesteric plate are derived. The selection rules for the twisted photons radiated at the harmonic $n\in \mathbb{Z}$ are established. In the paraxial regime, the projection of the orbital angular momentum of a radiated twisted photon obeys the selection rule $l=\pm(2n+1)$. In the approximation of a small anisotropy of the permittivity tensor, the selection rule becomes $m=\pm 2n$, where $m$ is the projection of the total angular momentum of a radiated twisted photon. The sign "$\pm$" in these selection rules is related to