Covariant Compton Amplitudes in Gravity with Classical Spin

TL;DR

This paper introduces a new amplitude bootstrap method for classical spinning particles interacting with gravitons, avoiding unphysical poles and leveraging double-copy and factorization limits, with potential to extend to all spin orders.

Contribution

It presents a novel amplitude bootstrap approach that is free of unphysical poles and applicable to high-spin gravitational Compton amplitudes, using only physical data and double-copy techniques.

Findings

Developed a pole-free amplitude bootstrap method

Addressed high-spin covariant gravitational Compton amplitudes

Identified a pattern potentially extendable to all spin orders

Abstract

We develop a novel amplitude bootstrap technique manifestly free of unphysical poles for classically spinning particles interacting with gravitons utilizing only the double-copy and physical factorization limits. Combined with non-factorization polynomial contact contributions from physical data for Kerr black holes, we can address high-spin-order covariant gravitational Compton amplitudes, identifying a pattern for the amplitude that we believe could extend to all orders in spin. Finally, we outline applications and outstanding questions.