High Energy Theory Seminar: Carlo Heissenberg

Title: Nonlinear gravitational memory from scattering amplitudes

Asbtract: Scattering amplitudes offer a convenient tool to recast gravitational-wave observables in terms of gauge-invariant building blocks. Amplitude methods are particularly relevant in the the post-Minkowskian (PM) regime, in which sources are far apart and interact weakly. A complementary approach is provided by soft theorems, which apply for small frequencies while retaining exact information on the hard dynamics. In this talk, I will discuss recent progress achieved by combining these two methods to calculate the waveform sourced by the scattering of two compact objects. In particular, I will show how the nonlinear memory effect emerges from amplitudes in the NNLO PM waveform, to leading order in the soft limit, and illustrate how its explicit calculation can be reduced to cut two-loop integrals.