A quantitative result for the $k$-Hessian equation
Alba Lia Masiello, Francesco Salerno
TL;DR
The paper develops a quantitative Polya-Szego-type theory for the $k$-Hessian equation by introducing a $(k-1)$-symmetrization that preserves quermassintegrals of sublevel sets. Leveraging the quantitative Alexandrov-Fenchel inequality and the Hausdorff asymmetry, it proves explicit deficit bounds for the $k$-Hessian functional under shape perturbations and derives a sharp comparison between the symmetrized and radially symmetric solutions. These results yield quantitative versions of Faber-Krahn and Saint-Venant-type inequalities, as well as eigenvalue and torsional rigidity stability statements in terms of the asymmetry of the domain. The approach unifies convex geometry with fully nonlinear PDE techniques and provides stability estimates for shape optimization problems involving the $k$-Hessian operator in high dimensions.
Abstract
In this paper, we study a symmetrization that preserves the mixed volume of the sublevel sets of a convex function, under which, a Pólya-Szeg\H o type inequality holds. We refine this symmetrization to obtain a quantitative improvement of the Pólya-Szeg\H o inequality for the $k$-Hessian integral, and, with similar arguments, we show a quantitative inequality for the comparison proved by Tso \cite{tso} for solutions to the $k$-Hessian equation. As an application of the first result, we prove a quantitative version of the Faber-Krahn and Saint-Venant inequalities for these equations.
