Proportionality of gravitational and electromagnetic radiation by an electron in an intense plane wave

TL;DR

This paper demonstrates a proportionality between gravitational and electromagnetic radiation emitted by an electron in an intense plane wave, linking classical and quantum descriptions through strong-field QED and quantum gravity.

Contribution

It establishes a proportionality between nonlinear graviton photoproduction and Compton scattering amplitudes in arbitrary plane waves, combining classical, semiclassical, and quantum approaches.

Findings

Proportionality holds at classical and quantum levels.

Amplitude of graviton photoproduction is proportional to Compton scattering.

Results connect gravity and electromagnetism in nonlinear quantum regimes.

Abstract

Accelerated charges emit both electromagnetic and gravitational radiation. Classically, it was found that the electromagnetic energy spectrum radiated by an electron in a monochromatic plane wave is proportional to the corresponding gravitational one. Quantum mechanically, it was shown that the amplitudes of graviton photoproduction and Compton scattering are proportional to each other at tree level. Here, by combining strong-field QED and quantum gravity, we demonstrate that the amplitude of nonlinear graviton photoproduction in an arbitrary plane wave is proportional to the corresponding amplitude of nonlinear Compton scattering. Also, introducing classical amplitudes we prove that the proportionality relies on the semiclassical nature of the electron's motion in a plane wave and on energy-momentum conservation laws, leading to the same proportionality constant in the classical and quantum case. These results deepen the intertwine between gravity and electromagnetism into both a nonlinear and a quantum level.