Optimisation of the lowest Robin eigenvalue in exterior domains of the hyperbolic plane

Fuente: arXiv
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Main Authors: Celentano, Antonio, Krejcirik, David, Lotoreichik, Vladimir
Format: Preprint
Published: 2026
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_version_ 1866909991387004928
author Celentano, Antonio
Krejcirik, David
Lotoreichik, Vladimir
author_facet Celentano, Antonio
Krejcirik, David
Lotoreichik, Vladimir
contents We consider the Robin Laplacian in the exterior of a bounded simply-connected Lipschitz domain in the hyperbolic plane. We show that the essential spectrum of this operator is $[\frac14,\infty)$ and that, under convexity assumption on the domain, there exist discrete eigenvalues below $\frac14$ if, and only if, the Robin parameter is below a non-positive critical constant, which depends on the shape of the domain. As the main result, we prove that the lowest Robin eigenvalue for the exterior of a bounded geodesically convex domain $Ω$ in the hyperbolic plane does not exceed such an eigenvalue for the exterior of the geodesic disk, whose geodesic curvature of the boundary is not smaller than the averaged geodesic curvature of the boundary of $Ω$. This result implies as a consequence that under fixed area or fixed perimeter constraints the exterior of the geodesic disk maximises the lowest Robin eigenvalue among exteriors of bounded geodesically convex domains. Moreover, we obtain under the same geometric constraints a reverse inequality between the critical constants.
format Preprint
id arxiv_https___arxiv_org_abs_2601_10280
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Optimisation of the lowest Robin eigenvalue in exterior domains of the hyperbolic plane
Celentano, Antonio
Krejcirik, David
Lotoreichik, Vladimir
Analysis of PDEs
Optimization and Control
Spectral Theory
35P15, 58J50, 52A55
We consider the Robin Laplacian in the exterior of a bounded simply-connected Lipschitz domain in the hyperbolic plane. We show that the essential spectrum of this operator is $[\frac14,\infty)$ and that, under convexity assumption on the domain, there exist discrete eigenvalues below $\frac14$ if, and only if, the Robin parameter is below a non-positive critical constant, which depends on the shape of the domain. As the main result, we prove that the lowest Robin eigenvalue for the exterior of a bounded geodesically convex domain $Ω$ in the hyperbolic plane does not exceed such an eigenvalue for the exterior of the geodesic disk, whose geodesic curvature of the boundary is not smaller than the averaged geodesic curvature of the boundary of $Ω$. This result implies as a consequence that under fixed area or fixed perimeter constraints the exterior of the geodesic disk maximises the lowest Robin eigenvalue among exteriors of bounded geodesically convex domains. Moreover, we obtain under the same geometric constraints a reverse inequality between the critical constants.
title Optimisation of the lowest Robin eigenvalue in exterior domains of the hyperbolic plane
topic Analysis of PDEs
Optimization and Control
Spectral Theory
35P15, 58J50, 52A55
url https://arxiv.org/abs/2601.10280