The quarter-gap conjecture for random hyperbolic surfaces with cusps

Let Mg,n(g)\mathcal{M}_{g,n(g)} be the moduli space of hyperbolic surfaces of genus gg with n(g)n(g) punctures, equipped with the Weil–Petersson probability measure, and let spec(X)\operatorname{spec}(X) denote the spectrum of a surface XX. Assume

limgn(g)g=0.\lim\limits_{g\to\infty}\frac{n(g)}{\sqrt g}=0.

Quarter-gap conjecture. For every ϵ>0\epsilon>0,

limgProbWPg(XMg,n(g); spec(X)(0,14ϵ)=)=1.\lim\limits_{g\to\infty}\operatorname{Prob_{WP}^{g}}\left(X\in\mathcal{M}_{g,n(g)};\ \operatorname{spec}(X)\cap\left(0,\frac{1}{4}-\epsilon\right)=\emptyset\right)=1.

This predicts that the lower bound in the established theorem for the regime n(g)=o(g)n(g)=o(\sqrt g) can be improved to the Selberg value 14\frac14, analogously to the conjectural optimal spectral gap for closed hyperbolic surfaces. The statement remains open.

Sources & referencesView supporting material

Primary source

Yang Shen and Yunhui Wu, “Arbitrarily small spectral gaps for random hyperbolic surfaces with many cusps”, arXiv:2203.15681 (2025).

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