Parameterized Parity Violation in Gravitational Wave Propagation

TL;DR

This paper introduces a new parametrization scheme for studying gravitational parity violation effects on wave propagation, enabling model-agnostic tests and mapping to existing formalisms like ppE, with implications for gravitational wave observations.

Contribution

It develops a generalized parametrization for parity violation in gravitational waves, linking it to theories beyond general relativity and existing waveform frameworks.

Findings

Amplitude and velocity birefringence scale with an effective distance measure.

The parametrization can be mapped to the ppE formalism for waveform analysis.

Existing constraints can be translated into bounds on parity-violating parameters.

Abstract

Gravitational parity violation arises in a variety of theories beyond general relativity. Gravitational waves in such theories have their propagation altered, leading to birefringence effects in both the amplitude and speed of the wave. In this work, we introduce a generalized, theory-motivated parametrization scheme to study parity violation in gravitational wave propagation. This parametrization maps to parity-violating gravity theories in a straightforward way. We find that the amplitude and velocity birefringence effects scale with an effective distance measure that depends on how the dispersion relation is modified. Furthermore, we show that this generic parametrization can be mapped to the parametrized-post-Einsteinian (ppE) formalism with convenient applications to gravitational wave observations and model-agnostic tests of general relativity. We derive a mapping to the standard ppE waveform of the gravitational wave response function, and also find a ppE waveform mapping at the level of the polarization modes, $h_+$ and $h_\times$. Finally, we show how existing constraints in the literature translate to bounds on our new parity-violating parameters and discuss avenues for future analysis.