Amplitudes for Astrophysicists: Known Knowns

TL;DR

This paper introduces modern on-shell computational methods from quantum field theory to astrophysics, demonstrating their effectiveness through light bending and gravitational wave scattering examples.

Contribution

It pioneers the application of recent high-energy physics techniques to astrophysical problems, bridging a gap between fields.

Findings

Modern on-shell methods simplify calculations in astrophysics.

Demonstrated application to gravitational wave scattering.

Enhanced computational efficiency over traditional approaches.

Abstract

The use of quantum field theory to understand astrophysical phenomena is not new. However, for the most part, the methods used are those that have been developed decades ago. The intervening years have seen some remarkable developments in computational quantum field theoretic tools. In particle physics, this technology has facilitated calculations that, even ten years ago would have seemed laughably difficult. It is remarkable, then, that most of these new techniques have remained firmly within the domain of high energy physics. We would like to change this. As alluded to in the title, this is the first in a series of papers aimed at showcasing the use of modern on-shell methods in the context of astrophysics and cosmology. In this first article, we use the old problem of the bending of light by a compact object as an anchor to pedagogically develop these new computational tools. Once developed, we then illustrate their power and utility with an application to the scattering of gravitational waves.