Complete spectrum of the Robin eigenvalue problem on the ball

Fuente: arXiv
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Main Authors: Dai, Guowei, Sun, Yingxin
Format: Preprint
Published: 2025
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author Dai, Guowei
Sun, Yingxin
author_facet Dai, Guowei
Sun, Yingxin
contents We investigate the following Robin eigenvalue problem \begin{equation*} \left\{ \begin{array}{ll} -Δu=μu\,\, &\text{in}\,\, B,\\ \partial_\texttt{n} u+αu=0 &\text{on}\,\, \partial B \end{array} \right. \end{equation*} on the unit ball of $\mathbb{R}^N$. We obtain the complete spectral structure of this problem. In particular, for $α>0$, the first eigenvalue is $k_{ν,1}^2$ and the second eigenvalue is $k_{ν+1,1}^2$, where $k_{ν+l,m}$ is the $m$th positive zero of $kJ_{ν+l+1}(k)-(α+l) J_{ν+l}(k)$. Moreover, when $α\in(-l,1-l)$ with any $l\in \mathbb{N}$, one has $l$ negative (strictly increasing) eigenvalues $-\widehat{k}_{ν+i,1}^2$ with $i\in\{0,\ldots,l-1\}$ where $\widehat{k}_{ν+l,1}$ denotes the unique zero of $αI_{ν+l}(k)+lI_{ν+l}(k)+kI_{ν+l+1}(k)$; while, for $α=-l$, besides $l$ negative (increasing) eigenvalues, $0$ is also an eigenvalue.
format Preprint
id arxiv_https___arxiv_org_abs_2510_26331
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Complete spectrum of the Robin eigenvalue problem on the ball
Dai, Guowei
Sun, Yingxin
Analysis of PDEs
Spectral Theory
34L20, 34L10, 35J05, 35P10, 35P20
We investigate the following Robin eigenvalue problem \begin{equation*} \left\{ \begin{array}{ll} -Δu=μu\,\, &\text{in}\,\, B,\\ \partial_\texttt{n} u+αu=0 &\text{on}\,\, \partial B \end{array} \right. \end{equation*} on the unit ball of $\mathbb{R}^N$. We obtain the complete spectral structure of this problem. In particular, for $α>0$, the first eigenvalue is $k_{ν,1}^2$ and the second eigenvalue is $k_{ν+1,1}^2$, where $k_{ν+l,m}$ is the $m$th positive zero of $kJ_{ν+l+1}(k)-(α+l) J_{ν+l}(k)$. Moreover, when $α\in(-l,1-l)$ with any $l\in \mathbb{N}$, one has $l$ negative (strictly increasing) eigenvalues $-\widehat{k}_{ν+i,1}^2$ with $i\in\{0,\ldots,l-1\}$ where $\widehat{k}_{ν+l,1}$ denotes the unique zero of $αI_{ν+l}(k)+lI_{ν+l}(k)+kI_{ν+l+1}(k)$; while, for $α=-l$, besides $l$ negative (increasing) eigenvalues, $0$ is also an eigenvalue.
title Complete spectrum of the Robin eigenvalue problem on the ball
topic Analysis of PDEs
Spectral Theory
34L20, 34L10, 35J05, 35P10, 35P20
url https://arxiv.org/abs/2510.26331