Spacelike reduction of the gravitational topological terms and associated helicity densities
Available on arXiv, 2026
This paper reduces the Pontryagin and Nieh‑Yang terms, defines four gravitational helicity densities under linearized SVT decomposition, and applies them to systems such as Newtonian binaries, weak‑field boosted Kerr black holes, gyratonic pp‑waves, and a linearized gravitational Hopfion.