Explicit fundamental gap estimates for some convex domains in $\mathbb{H}^2$

Theodora Bourni, Julie Clutterbuck, Xuan Hien Nguyen, Alina Stancu, Guofang Wei, Valentina‐Mira Wheeler

Abstract

Motivated by an example of Shih, we compute the fundamental gap of a family of convex domains in the hyperbolic plane $\mathbb H^2$, showing that for some of them $\lambda_2 - \lambda_1 < \frac{3\pi^2}{D^2}$, where $D$ is the diameter of the domain and $\lambda_1$, $\lambda_2$ are the first and second Dirichlet eigenvalues of the Laplace operator on the domain. The result contrasts with what is known in $\mathbb R^n $ or $\mathbb S^n$, where $\lambda_2 - \lambda_1 \geq \frac{3 \pi^2}{D^2}$ for convex domains. We also show that the fundamental gap of the example in Shih's article is still greater than $\tfrac 32 \frac{\pi^2}{D^2}$, even though the first eigenfunction of the Laplace operator is not log-concave.

Locations

• Mathematical Research Letters - View - PDF
• arXiv (Cornell University) - View - PDF