Besov spaces and Schatten class Hankel operators for Hardy and Paley--Wiener spaces in higher dimensions
Konstantinos Bampouras, Karl-Mikael Perfekt
TL;DR
The paper develops a unified framework connecting Schatten-class Hankel operators on Paley--Wiener spaces to Besov regularity adapted to domain geometry. By introducing geometry-aware weights $\omega_{\Omega}$ and Besov spaces $B_{p,p}^{s}(2\Omega)$ built from admissible parallelepiped covers, it characterizes Hankel operator membership $\mathop{H}_{\varphi}^{\sigma,\tau}\in S^{p}$ (for $1\le p\le 2$) precisely as $\varphi\in B_{p,p}^{\sigma+\tau+\frac{1}{p}}(2\Omega)$, with extensions to all $1\le p<\infty$ on product Hardy spaces and to $p<2(n+1)/(n-1)$ for bounded smooth domains. The work combines Macbeath-region geometry, kernel estimates, and interpolation to yield a robust, geometry-aware Schatten-class theory for high-dimensional Hankel operators, including special cases for polytopes and product spaces. It also raises open questions about admissibility and convolution-type inequalities for the weight $\omega_{\Omega}$, guiding future development of Paley--Wiener Besov theory in irregular domains.
Abstract
We consider Schatten class membership of Hankel operators on Paley--Wiener spaces of convex $Ω\subset \mathbb{R}^n$, both for bounded and unbounded domains. In particular, the classical product Hardy spaces fit within our theory. For admissible domains, we develop a framework and theory of Besov spaces of Paley--Wiener type, and prove that a Hankel operator belongs to the Schatten class $S^p$ if and only if its symbol belongs to a corresponding Besov space, for $1 \leq p \leq 2$. We extend this result to all $1 \leq p < \infty$ for the classical product Hardy spaces and to $1 \leq p < 2(n+1)/(n-1)$ for the Paley--Wiener space of a bounded smooth domain $Ω\subset \mathbb{R}^n$ of strictly positive curvature.
