soft graviton theorem



In perturbative quantum gravity, the soft graviton theorem (Weinberg 65) re-formulates scattering amplitudes of a set of finite energy external particles with one or more low energy external gravitons, in terms of the amplitude without the low energy gravitons.

In the classical limit, there is a different manifestation of the same theorem (Saha-Sahoo-Sen 19): here it determines the low frequency component of the gravitational wave-form produced during a scattering process in terms of the momenta and spin of the incoming and outgoing objects, without any reference to the interactions responsible for the scattering.


Original reference:

Review with focus on photons in electromagnetism:

Discussion of application to gravitational waves in the classical limit: