Published Paper

Inserted: 3 jun 2013
Last Updated: 30 oct 2017

Journal: Duke Math. J.
Volume: 164
Number: 9
Pages: 1777-1832
Year: 2015

Abstract:

The classical Faber-Krahn inequality asserts that balls (uniquely) minimize the first eigenvalue of the Dirichlet-Laplacian among sets with given volume. In this paper we prove a sharp quantitative enhancement of this result, thus confirming a conjecture by Nadirashvili and Bhattacharya-Weitsman. More generally, the result applies to every optimal Poincar\'e-Sobolev constant for the embeddings $W^{1,2}_0(\Omega)\hookrightarrow L^q(\Omega)$.

Keywords: Stability for eigenvalues, Torsional rigidity, regularity for free boundaries

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