Probe the gravitational constant variation via the propagation of gravitational waves

TL;DR

This paper investigates how variations in the gravitational constant influence the propagation of gravitational waves, revealing amplitude and phase corrections that can aid in testing the strong equivalence principle.

Contribution

It introduces two analytical methods to derive the gravitational wave equation considering gravitational constant variation, showing consistent results and potential for data analysis.

Findings

Small variations cause amplitude corrections in gravitational waves.

Phase corrections appear at sub-leading order.

Results align with previous Maxwell-like equation studies.

Abstract

The gravitational constant variation means the breakdown of the strong equivalence principle. As the cornerstone of general relativity, the validity of general relativity can be examined by studying the gravitational constant variation. Such variations have the potential to affect both the generation and propagation of gravitational waves. In this paper, our focus lies on the effect of gravitational constant variation specifically on the propagation of gravitational waves. We employ two analytical methods, namely based on the Fierz-Pauli action and the perturbation of Einstein-Hilbert action around Minkowski spacetime, both leading to the the same gravitational wave equation. By solving this equation, we find the effects of gravitational constant variation on gravitational wave propagation. The result is consistent with previous investigations based on Maxwell-like equations for gravitational waves. Notably, we find that small variations in the gravitational constant result in an amplitude correction at the leading order and a phase correction at the sub-leading order for gravitational waves. These results provide valuable insights for probing gravitational constant variation and can be directly applied to gravitational wave data analysis.