A note on the log-perturbed Br\'ezis-Nirenberg problem on the hyperbolic space

TL;DR

This paper investigates a log-perturbed nonlinear elliptic problem on hyperbolic space, establishing existence of solutions for positive perturbation parameters and non-existence for negative ones, using asymptotic decay estimates.

Contribution

It provides the first detailed analysis of the log-perturbed Brézis-Nirenberg problem on hyperbolic space, especially handling the sign-changing perturbation.

Findings

Existence of solutions for  when  > 0.

Non-existence of positive solutions for  < 0.

Derived asymptotic decay estimates for solutions.

Abstract

We consider the log-perturbed Br\'ezis-Nirenberg problem on the hyperbolic space \begin{align*} \Delta_{\mathbb{B}^N}u+\lambda u +|u|^{p-1}u+\theta u \ln u^2 =0, \ \ \ \ u \in H^1(\mathbb{B}^N), \ u > 0 \ \mbox{in} \ \mathbb{B}^N, \end{align*} and study the existence vs non-existence results. We show that whenever $\theta >0,$ there exists an $H^1$-solution, while for $\theta <0$, there does not exist a positive solution in a reasonably general class. Since the perturbation $ u \ln u^2$ changes sign, Pohozaev type identities do not yield any non-existence results. The main contribution of this article is obtaining an "almost" precise lower asymptotic decay estimate on the positive solutions for $\theta <0,$ culminating in proving their non-existence assertion.