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arXiv · 2405.09687

Scattering and bound observables for spinning particles in Kerr spacetime with generic spin orientations

Riccardo Gonzo·Canxin Shi
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Abstract

We derive the radial action of a spinning probe particle in Kerr spacetime from the worldline formalism in the first-order form, focusing on linear in spin effects. We then develop a novel covariant Dirac bracket formalism to compute the impulse and the spin kick directly from the radial action, generalizing some conjectural results in the literature and providing ready-to-use expressions for amplitude calculations with generic spin orientations. This allows, for the first time, to find new covariant expressions for scattering observables in the probe limit up to $\mathcal{O}(G^6 s_1 s_2^4)$. Finally, we use the action-angle representation to compute the fundamental frequencies for generic bound orbits, including the intrinsic spin precession, the periastron advance and the precession of the orbital plane.

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Riccardo Gonzo, Canxin Shi. 2024-05-15. Scattering and bound observables for spinning particles in Kerr spacetime with generic spin orientations. https://doi.org/10.1103/physrevlett.133.221401

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