Spectral gap for Weil-Petersson random surfaces with cusps

Abstract

We show that for any $\epsilon>0$, $\alpha\in[0,\frac{1}{2})$, as $g\to\infty$ a generic finite-area genus g hyperbolic surface with $n=O\left(g^{\alpha}\right)$ cusps, sampled with probability arising from the Weil-Petersson metric on moduli space, has no non-zero eigenvalue of the Laplacian below $\frac{1}{4}-\left(\frac{2\alpha+1}{4}\right)^{2}-\epsilon$. For $\alpha=0$ this gives a spectral gap of size $\frac{3}{16}-\epsilon$ and for any $\alpha<\frac{1}{2}$ gives a uniform spectral gap of explicit size.