Classical observables of General Relativity from scattering amplitudes in the PM expansion
We start discussing the elastic scattering of two massive particles with different masses and from their scattering amplitude we extract the eikonal that is a classical quantity and from it the classical deflection angle up to 3PM (two loops).
Then, we consider the inelastic process in which an extra soft graviton is emitted in the final state and we show how in this case the c-number elastic eikonal becomes an operator containing the creation and annihilation operators of the graviton. Then we compute the waveform and the zero frequency limit (ZFL) of the emitted energy.
Finally we show that both the elastic and inelastic observables are universal at high energy as expected from the fact that the graviton is the massless particle with the highest spin.
the 15th November 2022, 14:30