A Weyl's Law for Singular Riemannian Foliations with Applications to Invariant Theory
Samuel Lin, Ricardo A. E. Mendes, Marco Radeschi
TL;DR
The paper develops a Weyl-type asymptotic for the basic spectrum of closed singular Riemannian foliations with basic mean curvature, proving N(t) ~ ${\operatorname{vol}(X)\omega_m\over (2\pi)^m} t^{m/2}$ for the leaf space X = M/\mathcal{F} (m = dim X). In the special case M = \mathbb{S}^n, it yields a formula expressing Vol(\mathbb{S}^n/\mathcal{F}) as a rational multiple of Vol(\mathbb{S}^m$, linked to the algebra of basic polynomials via the Laplacian algebra A and its Hilbert series H(z). The approach fuses averaging over leaves, slice-theoretic local models, Hörmander asymptotics, heat-kernel analysis, and Tauberian theorems, with an invariant-theory backbone showing A is Cohen–Macaulay and finitely generated, and connecting spectral data to Hilbert-series coefficients. The paper also provides explicit, representation-theoretic analogues and examples (e.g., Clifford foliations, Hopf fibrations) and discusses generalizations to manifold submetries. This work sharpens the understanding of spectral geometry on singular foliations and their quotient spaces, with implications for invariant theory and geometric analysis on singular spaces.
Abstract
We prove a version of Weyl's Law for the basic spectrum of a closed singular Riemannian foliation $(M,\mathcal{F})$ with basic mean curvature. In the special case of $M=\mathbb{S}^n$, this gives an explicit formula for the volume of the leaf space $\mathbb{S}^n/\mathcal{F}$ in terms of the algebra of basic polynomials. In particular, $\operatorname{Vol}(\mathbb{S}^n/\mathcal{F})$ is a rational multiple of $\operatorname{Vol}(\mathbb{S}^m)$, where $m=\dim (\mathbb{S}^n/\mathcal{F})$.
