2025/06/06 by Alexis de Villeroché, de Villeroché, Alexis
Engineering · Mathematics · #Analysis of PDEs (math.AP) #FOS: Mathematics #Nonlinear Partial Differential Equations #Spectral Theory in Mathematical Physics #Stability and Controllability of Differential Equations
paper · pdf · doi:10.48550/arxiv.2506.05870
openalex publication_date 2025/06/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Let Ω⊂ ℝd be an open set of finite measure and let Θ be a disjoint union of two balls of half measure. We study the stability of the full Dirichlet spectrum of Ω when its second eigenvalue is close to the second eigenvalue of Θ. Precisely, for every integer k ≥ 1, we provide a quantitative control of the difference |λk(Ω)-λk(Θ)| by the variation of the second eigenvalue C(d,k)(λ2(Ω)-λ2(Θ))α, for a suitable exponent α and a positive constant C(d,k) depending only on the dimension of the space and the index k. We are able to find such an estimate for general k and arbitrary Ω with α=αd/(d+1)2 where α2 = 1/2 and 0<αd<1 in higher dimensions. In the particular case where λk(Ω)≥ λk(Θ), we can improve the inequality and find an estimate with the sharp exponent α= 1/2.