Spectra of infinitesimal generators of composition semigroups on weighted Bergman spaces induced by doubling weights
Ruishen Qian, Fanglei Wu, Hasi Wulan
TL;DR
The paper addresses the problem of describing the spectrum of the infinitesimal generator $\Gamma$ of a composition semigroup on the doubling-weighted Bergman space $A^p_\omega$ by elliptic semigroups. It combines a spectral mapping theorem with detailed spectra of composition operators, and establishes an eventual norm continuity framework to enable SMT-based spectral descriptions. Key contributions include explicit descriptions of the spectrum and point spectrum in terms of Koenigs data and spiral-like growth of the Koenigs image, a Carleson-measure–based criterion for eventual norm continuity, a resolvent representation $R(\lambda,\Gamma)$ when the Denjoy-Wolff point is $0$, and the introduction of the operator $R_h$ whose boundedness/compactness on $A^p_\omega$ is tied to the smoothness class of $\log\frac{h(z)}{z}$. These results extend known Hardy and standard Bergman space findings to doubling-weight settings and provide concrete tools for analyzing resolvents and spectral properties of composition semigroups.
Abstract
Suppose $(C_t)_{t\geq0}$ is the composition semigroup induced by a one-parameter semigroup $(\varphi_t)_{t\geq0}$ of analytic self-maps of the unit disk. The main purpose of the paper is to investigate the spectrum of the infinitesimal generator of $(C_t)_{t\geq0}$ acting on the weighted Bergman space induced by doubling weights, provided $(\varphi_t)_{t\geq0}$ is elliptic. The method applied is a certain spectral mapping theorem and a characterization of the spectra of certain composition operators. Eventual norm-continuity of $(C_t)_{t\geq0}$ also plays an important role, which can be depicted in terms of studying the difference of two distinct composition operators. As a byproduct, we also characterize a certain compact integral operator that is closely related to the resolvent of the infinitesimal generator of $(C_t)_{t\geq0}$.
