Normal, cohyponormal and normaloid weighted composition operators on the Hardy and weighted Bergman spaces

TL;DR

This paper characterizes normal, cohyponormal, hyponormal, and normaloid weighted composition operators on Hardy and weighted Bergman spaces, providing conditions on symbols for these properties and identifying all bounded below normal operators.

Contribution

It offers new characterizations of weighted composition operators' properties on Hardy and Bergman spaces, including conditions on symbols and classifications for specific automorphisms.

Findings

Cohyponormality implies non-vanishing symbol and univalence of the composition function.

Complete characterization of normal, cohyponormal, and hyponormal operators with specific symbols.

Identification of all bounded below normal weighted composition operators.

Abstract

If $\psi$ is analytic on the open unit disk $\mathbb{D}$ and $\varphi$ is an analytic self-map of $\mathbb{D}$, the weighted composition operator $C_{\psi,\varphi}$ is defined by $C_{\psi,\varphi}f(z)=\psi(z)f (\varphi (z))$, when $f$ is analytic on $\mathbb{D}$. In this paper, we study normal, cohyponormal, hyponormal and normaloid weighted composition operators on the Hardy and weighted Bergman spaces. First, for some weighted Hardy spaces $H^{2}(\beta)$, we prove that if $C_{\psi,\varphi}$ is cohyponormal on $H^{2}(\beta)$, then $\psi$ never vanishes on $\mathbb{D}$ and $\varphi$ is univalent, when $\psi \not \equiv 0$ and $\varphi$ is not a constant function. Moreover, for $\psi=K_{a}$, where $|a| < 1$, we investigate normal, cohyponormal and hyponormal weighted composition operators $C_{\psi,\varphi}$. After that, for $\varphi $ which is a hyperbolic or parabolic automorphism, we characterize all normal weighted composition operators $C_{\psi,\varphi}$, when $\psi \not \equiv 0$ and $\psi$ is analytic on $\overline{\mathbb{D}}$. Finally, we find all normal weighted composition operators which are bounded below.