Conservative binary dynamics from gravitational tail emission processes

We re-analyze the far zone contribution to the two-body conservative dynamics arising from interaction between radiative and longitudinal modes, the latter sourced by mass and angular momentum, which in the mass case is known as tail process. We verify the expected correspondence between two loop self-energy amplitudes and the gluing of two classical (one leading order, one at one loop) emission amplitudes. In particular we show that the factorization of the self-energy amplitude involving the angular momentum is violated when applying standard computation procedures, due to a violation of the Lorentz gauge condition commonly adopted in perturbative computations. We show however that a straightforward fix exists, as the violation corresponds to a consistent anomaly, and it can be re-absorbed by the variation of a suitable action functional.