A Gauss-Bonnet formula for the renormalized area of minimal submanifolds of Poincaré-Einstein manifolds
Jeffrey S. Case, C Robin Graham, Tzu-Mo Kuo, Aaron J. Tyrrell, Andrew Waldron
TL;DR
The paper proves a Gauss–Bonnet-type formula for the renormalized area of even-dimensional minimal submanifolds Y in Poincaré–Einstein manifolds X by postulating a submanifold analog of Alexakis' decomposition of conformal invariants. The extrinsic Q-curvature I on Y is conjectured to decompose as I = c Pf + W_Q + div V, which yields renormalized-area expressions A = c_k χ(Y) + ((-1)^{k/2}/(k-1)!) ∫_Y W_Q dA when i:Y→X is polyhomogeneous and the ambient metric is Poincaré–Einstein. The authors verify the conjecture in dimensions k = 2 and k = 4, derive explicit forms for the corresponding W_Q, and connect these with known invariants in the literature; they also provide a renormalized-area formula for minimal submanifolds of Einstein manifolds. The work advances conformal submanifold geometry by producing a robust, invariant integrand for renormalized quantities and ties holographic-type renormalization to intrinsic topological data via the Euler characteristic.
Abstract
Assuming the extrinsic $Q$-curvature admits a decomposition into the Pfaffian, a scalar conformal submanifold invariant, and a tangential divergence, we prove that the renormalized area of an even-dimensional minimal submanifold of a Poincaré-Einstein manifold can be expressed as a linear combination of its Euler characteristic and the integral of a scalar conformal submanifold invariant. We derive such a decomposition of the extrinsic $Q$-curvature in dimensions two and four, thereby recovering and generalizing results of Alexakis-Mazzeo and Tyrrell, respectively. We also conjecture such a decomposition for general natural submanifold scalars whose integral over compact submanifolds is conformally invariant, and verify our conjecture in dimensions two and four. Our results also apply to the area of a compact even-dimensional minimal submanifold of an Einstein manifold.
