Conveners
Angular momentum loss at O(G^4) from worldline QFT
- Kathrin Stoldt
Description
In a black hole scattering event, the two-body system emits gravitational waves. Information about these dissipative effects is stored in the angular momentum loss and the energy radiated away. It is therefore a natural task to calculate these observables analytically to high perturbative orders. These results may then be used to inform and improve gravitational waveform models. In the past few years, we have seen tremendous progress in the calculation of the radiated energy, reaching the fifth post-Minkowskian order. Recently, the loss of angular momentum has caught up to the fourth post-Minkowskian order. This result was obtained in two different approaches: our calculation centres on the mechanical angular momentum, while the other independent computation focusses on the radiative loss, with both arriving at the same result. In this talk, I will discuss how we used the worldline quantum field theory formalism to calculate the mechanical loss of angular momentum from the change in the impact parameter at this order. The calculation can be split into two regions, dynamical and static, which are treated individually. I will show the striking similarity of the dynamical part to the impulse, as well as how to obtain the static part and its relation to linear and nonlinear memory.