Scattering of Long-Wavelength Gravitational Waves

TL;DR

This paper analyzes how low-frequency gravitational waves scatter off massive bodies, using partial-wave methods to accurately compute scattering amplitudes and clarify previous conflicting results.

Contribution

It provides a detailed partial-wave analysis of gravitational wave scattering, confirming agreement with perturbation theory and correcting earlier claims.

Findings

Partial-wave cross section matches perturbation theory results.

Helicity-conserving and reversing contributions are computed accurately.

First-order $M\omega$ corrections are included.

Abstract

We consider the scattering of a low-frequency gravitational wave by a massive compact body in vacuum. We apply partial-wave methods to compute amplitudes for the helicity-conserving and helicity-reversing contributions to the cross section, accurate to first order in $M\omega$. Contrary to previous claims, we find that the partial-wave cross section agrees with the cross section derived via perturbation-theory methods.