Next-to-leading order gravitational spin-orbit coupling in an effective field theory approach

TL;DR

This paper employs an effective field theory approach to compute the next-to-leading order gravitational spin-orbit interaction between two spinning compact objects, advancing the precision of gravitational wave modeling.

Contribution

It introduces an efficient EFT calculation method for NLO spin-orbit effects, including non-stationary interactions and higher-order spin supplementary conditions, with explicit relation to canonical formalisms.

Findings

Derived NLO spin-orbit interaction using EFT

Included non-stationary cubic self-gravitational interactions

Connected EFT results to ADM Hamiltonian formalism

Abstract

We use an effective field theory (EFT) approach to calculate the next to leading order (NLO) gravitational spin-orbit interaction between two spinning compact objects. The NLO spin-orbit interaction provides the most computationally complex sector of the NLO spin effects, previously derived within the EFT approach. In particular, it requires the inclusion of non-stationary cubic self-gravitational interaction, as well as the implementation of a spin supplementary condition (SSC) at higher orders. The EFT calculation is carried out in terms of the non-relativistic gravitational field parametrization, making the calculation more efficient with no need to rely on automated computations, and illustrating the coupling hierarchy of the different gravitational field components to the spin and mass sources. Finally, we show explicitly how to relate the EFT derived spin results to the canonical results obtained with the ADM Hamiltonian formalism. This is done using non-canonical transformations, required due to the implementation of covariant SSC, as well as canonical transformations at the level of the Hamiltonian, with no need to resort to the equations of motion or the Dirac brackets.