Chiral Imprint of a Cosmic Gauge Field on Primordial Gravitational Waves

TL;DR

This paper demonstrates that a cosmological gauge field can induce parity violation in primordial gravitational waves, leading to detectable polarization asymmetries in the cosmic microwave background.

Contribution

It introduces a novel mechanism where a cosmological gauge field causes parity violation in gravitational waves, affecting CMB polarization patterns.

Findings

Primordial gravitational waves develop a preferred polarization handedness.

Parity-violating correlations in CMB temperature and polarization are predicted.

Detectable signatures could be observed by current and future experiments.

Abstract

A cosmological gauge field with isotropic stress-energy introduces parity violation into the behavior of gravitational waves. We show that a primordial spectrum of inflationary gravitational waves develops a preferred handedness, left- or right-circularly polarized, depending on the abundance and coupling of the gauge field during the radiation era. A modest abundance of the gauge field would induce parity-violating correlations of the cosmic microwave background temperature and polarization patterns that could be detected by current and future experiments.