Regularity of Critical Points of Scale-Invariant Geometric Energies for Even-Dimensional Submanifolds of $\mathbb R^m$

Abstract

We consider scale-invariant curvature energies for immersions of closed manifolds of even dimension $n=2h$ into $\mathbb R^m$, with principal term $\int_{\Sigma} \big|\nabla^{(h-1)} \vec{\mathrm{I\!I}}\big|_g^2\,d\text{vol}_g$ and arbitrary lower-order polynomial extrinsic invariants of the same scaling. Following the four-dimensional approach developed in joint work with Bernard, Martino, and Rivi\`ere, we prove that every weak critical immersion in the natural Sobolev class $W^{h+1,2}$, whose induced metric and its inverse have $L^\infty$ coefficients, is real-analytic in harmonic coordinates. The proof combines geometric conservation laws, additional structural identities, and elliptic estimates with critical Sobolev coefficients to obtain Morrey decay and bootstrap to full regularity.