Joint Theory Seminar: Andreas Brandhuber
Title: Spinning waveforms in (modified) GR from amplitudes
Abstract: We will report on recent progress on obtaining classical observables in general relativity from a heavy-mass effective theory. After an introduction we focus on the radiation produced by the scattering of two heavy scalars or spinning particles modelling Schwarzschild and Kerr blackholes respectively. We will describe how the corresponding five-point amplitudes can be used to extract waveforms via the observable based KMOC approach.
We will discuss the case of scalars at one-loop and the case of spinning celestial objects (Kerr black holes) at leading order. Using this result, we will then turn to the computation of the leading-order time-domain gravitational waveform. We will in particular focus on GR deformed by cubic-in-Riemann-tensor terms (the leading corrections). The method we describe is suitable for arbitrary values of classical spin of Kerr black holes and does not require any expansion in powers of the spin.