Gravity seminar - Riccardo Gonzo [UNUSUAL DAY AND PLACE] Seminar

Abstract: We discuss how to compute scattering waveforms for the classical two-body problem purely from on-shell five-point amplitudes, generalizing the KMOC (in-in) approach to radiative observables. Restricting to the case of two Kerr black-holes, we derive the time-domain waveform at leading order in the Post-Minkowskian expansion and at quartic order in the spin by using analyticity arguments to bypass the conventional observable phase-space integration. The result is expressed only in terms of the three-point amplitude and the four-point Compton amplitude, which makes it easier to generalize for the case of generic spinning bodies (i.e. with tidal effects). Finally, I will show how we can analytically continue the waveform from hyperbolic to (eccentric) bound orbits.