Andrea Cristofoli (NBI)

Title: The on-shell highway to waveforms

Abstract:

The KMOC approach, developed by David Kosower, Ben Maybee and Donal O’Connell, is an on-shell formalism that expresses classical observables in terms of quantum scattering amplitudes. After a first review, we will show how to generalize the original framework by including coherent states of massless bosons. This will allows us to describe classical wave phenomena naturally in terms of on-shell quantities. As an example, we will recompute the classic deflection of light and show how to rederive the impulse in the Thomson scattering. We will also see how to go beyond global observables to compute local ones such as the electromagnetic and gravitational Newman–Penrose scalars. As an application, we will see how to compute the radiated waveform in charged-particle scattering, showing at the end of the talk how it is linked directly to the expectation of the classical field.