# Existence of nonradial positive and nodal solutions to a critical Neumann problem in a cone

## TL;DR

This paper proves the existence of nonradial positive and sign-changing solutions to a critical Neumann problem in unbounded cones under certain geometric conditions, expanding understanding of solutions in non-spherical domains.

## Contribution

It establishes the existence of nonradial solutions to a critical Neumann problem in cones, including sign-changing and positive solutions, under convexity and volume conditions.

## Key findings

- Existence of nonradial sign-changing solutions under symmetry.
- Existence of positive nonradial solutions when cone volume is large.
- Solutions are found in unbounded cone domains with Neumann boundary conditions.

## Abstract

We study the critical Neumann problem \begin{equation*} \begin{cases} -\Delta u = |u|^{2^*-2}u &\text{in }\Sigma_\omega,\\ \quad\frac{\partial u}{\partial\nu}=0 &\text{on }\partial\Sigma_\omega, \end{cases} \end{equation*} in the unbounded cone $\Sigma_\omega:=\{tx:x\in\omega\text{ and }t>0\}$, where $\omega$ is an open connected subset of the unit sphere $\mathbb{S}^{N-1}$ in $\mathbb{R}^N$ with smooth boundary, $N\geq 3$ and $2^*:=\frac{2N}{N-2}$. We assume that some local convexity condition at the boundary of the cone is satisfied. If $\omega$ is symmetric with respect to the north pole of $\mathbb{S}^{N-1}$, we establish the existence of a nonradial sign-changing solution. On the other hand, if the volume of the unitary bounded cone $\Sigma_\omega\cap B_1(0)$ is large enough (but possibly smaller than half the volume of the unit ball $B_1(0)$ in $\mathbb{R}^N$), we establish the existence of a positive nonradial solution.