Stability inequalities for one-phase cones
Benjy Firester, Raphael Tsiamis, Yipeng Wang
TL;DR
This work establishes strict stability for the homogeneous one-phase Bernoulli cones with $O(n-k)\times O(k)$ symmetry in dimensions $n\ge7$, showing that all axisymmetric cones $U_{n,k}$ are strictly stable and deriving a bound on the first eigenvalue together with Jacobi-field decay rates. The analysis reduces stability to a one-dimensional Robin eigenvalue problem on the spherical link and exploits a detailed hypergeometric-function framework for the cone profiles $f_{n,k}$, complemented by Riccati-type subsolution constructions to produce global barriers. Consequently, the results yield implications for generic regularity of the Alt-Caffarelli one-phase problem and related free boundary models (capillary, fractional, Alt-Phillips), linking stability to minimization and rigidity phenomena. Furthermore, the paper provides concrete estimates for indicial roots and first-eigenvalue behavior across the $U_{n,k}$ family, and lays groundwork for a conjecture that the maximal eigenvalue is attained at $k=n-2$, with further validation forthcoming in related work.
Abstract
We obtain strict stability inequalities for homogeneous solutions of the one-phase Bernoulli problem. We prove that in dimension $7$ and above, cohomogeneity one solutions with bi-orthogonal symmetry are strictly stable. As a consequence, we obtain a bound on the first eigenvalue and the decay rates of Jacobi fields, with applications to the generic regularity of the one-phase problem.
