Chirality and Circular Polarization in Models of Inflation

TL;DR

This paper explores how chiral asymmetry during inflation can lead to net circular polarization in photons, potentially observable in the Cosmic Microwave Background, revealing new insights into early universe physics.

Contribution

It demonstrates that inflationary chiral asymmetry can produce measurable circular polarization in photons, linking inflation dynamics to CMB polarization signals.

Findings

Superhorizon photon modes acquire net circular polarization during inflation.

Reentering modes can thermalize into the CMB while retaining polarization.

Potential for direct detection of circular polarization in the CMB.

Abstract

We investigate the possibility that a chiral asymmetry during inflation can manifest as net circular polarization in photons. Using an example known to produce a helicity imbalance in fermions, we show that superhorizon photon modes produced during inflation acquire net circular polarization. Modes that reenter the horizon around last scattering can thermalize into the Cosmic Microwave Background while retaining a portion of their net circular polarization. We also consider the possibility of direct detection of the circular polarization in the CMB.