Cherenkov radiation in isotropic chiral matter: the space-frequency domain

TL;DR

This paper derives exact, gauge-invariant expressions for Cherenkov radiation in isotropic chiral matter, revealing unique spectral features, multiple Cherenkov cones, and threshold-free radiation in certain frequency regimes.

Contribution

It provides the first explicit formulas for circularly polarized Cherenkov fields in chiral media, highlighting novel phenomena like multiple cones and threshold-free radiation.

Findings

Spectral energy distributions are gauge-invariant and positive.

Multiple Cherenkov cones can occur depending on frequency.

Threshold-free Cherenkov radiation is possible for slow charges.

Abstract

The electromagnetic response of isotropic chiral matter, as described by Carroll-Field-Jackiw electrodynamics, arises in distinct physical contexts ranging from condensed matter systems to Lorentz-violating extensions of high-energy physics. Here, we derive exact expressions for the circularly polarized electromagnetic fields that contribute independently to Cherenkov radiation in isotropic chiral matter. Each spectral energy distribution is gauge-invariant and positive, yielding radiation that emerges at a characteristic angle, akin to the standard case. Furthermore, we identify specific frequency ranges that permit zero, one, or two Cherenkov cones for a given setup. Remarkably, one sector of the model allows for the existence of threshold-free Cherenkov radiation arising from slowly-moving charges.