Speaker
Description
I will present a novel method to compute classical observables for two-body scattering systems. The on-shell radial action is treated as a generating function to directly extract observables, with full spin dependence. To account for the spin supplementary condition and other constraints, we compute the corresponding Dirac brackets. The observables, such as momentum impulse and spin kick, are obtained by iteratively applying a differential operator, constructed by inserting the radial action into the first slot of the Dirac bracket, to the initial value of the observable. As an explicit case, we consider a spinning probe in the Kerr background and compute the radial action up to O(G^6 s^4). It is then used to efficiently calculate the momentum impulse and spin kick. Via analytic continuation, this radial action also provides information about bound orbits such as their fundamental frequencies.
