Effect of VSR invariant Chern-Simon Lagrangian on photon polarization

TL;DR

This paper explores how a generalized, SIM(2)-invariant Chern-Simons Lagrangian affects photon polarization over cosmological distances, finding it induces circular polarization and setting observational limits.

Contribution

It introduces a new Lorentz-violating Chern-Simons term invariant under SIM(2) and analyzes its impact on photon polarization in cosmological contexts.

Findings

The generalized Lagrangian induces circular polarization in propagating photons.

Observational data constrains the strength of the Lorentz-violating term.

The effect is significant over cosmological distances.

Abstract

We propose a generalization of the Chern-Simon (CS) Lagrangian which is invariant under the SIM(2) transformations but not under the full Lorentz group. We study the effect of such a term on radiation propagating over cosmological distances. We find that the dominant effect of this term is to produce circular polarization as radiation propagates through space. We use the circular polarization data from distant radio sources in order to impose a limit on this term.