Rigidity Theorems for Asymptotically Euclidean $Q$-singular Spaces
Rodrigo Avalos, Paul Laurain, Nicolas Marque
TL;DR
This work studies rigidity for fourth‑order curvature phenomena on asymptotically Euclidean (AE) manifolds, centering on $Q$-curvature and the tensor $J_g$ as a fourth‑order analogue of the Ricci tensor. The authors relate the fourth‑order energy $\,\mathcal{E}(g)$ to the asymptotic flux of the J‑Einstein tensor $G_J$ at infinity, establishing a conservation identity analogous to the ADM mass framework and leveraging a positive energy theorem. They prove that if $J_g=0$ and the Yamabe invariant $Y([g])>0$, then the AE manifold must be Euclidean, with a bootstrap mechanism showing that $J$‑flatness controls optimal decay via harmonic coordinates. Overall, the paper extends a Ricci‑flat rigidity paradigm to a fourth‑order, $Q$‑curvature–driven setting and provides precise decay control for geometric tensors on AE manifolds.
Abstract
In this paper we prove some rigidity theorems associated to $Q$-curvature analysis on asymptotically Euclidean (AE) manifolds, which are inspired by the analysis of conservation principles within fourth order gravitational theories. A central object in this analysis is a notion of fourth order energy, previously analysed by the authors, which is subject to a positive energy theorem. We show that this energy can be more geometrically rewritten in terms of a fourth order analogue to the Ricci tensor, which we denote by $J_g$. This allows us to prove that Yamabe positive $J$-flat AE manifolds must be isometric to Euclidean space. As a by product, we prove that this $J$-tensor provides a geometric control for the optimal decay rates at infinity. This last result reinforces the analogy of $J$ as a fourth order analogue to the Ricci tensor.
