No Arabic abstract
We study a Toeplitz type operator $Q_mu$ between the holomorphic Hardy spaces $H^p$ and $H^q$ of the unit ball. Here the generating symbol $mu$ is assumed to a positive Borel measure. This kind of operator is related to many classical mappings acting on Hardy spaces, such as composition operators, the Volterra type integration operators and Carleson embeddings. We completely characterize the boundedness and compactness of $Q_mu:H^pto H^q$ for the full range $1<p,q<infty$; and also describe the membership in the Schatten classes of $H^2$. In the last section of the paper, we demonstrate the usefulness of $Q_mu$ through applications.
Let $mathcal{D}$ be the class of radial weights on the unit disk which satisfy both forward and reverse doubling conditions. Let $g$ be an analytic function on the unit disk $mathbb{D}$. We characterize bounded and compact Volterra type integration operators [ J_{g}(f)(z)=int_{0}^{z}f(lambda)g(lambda)dlambda ] between weighted Bergman spaces $L_{a}^{p}(omega )$ induced by $mathcal{D}$ weights and Hardy spaces $H^{q}$ for $0<p,q<infty$.
The main purpose of this paper is to extend and refine some work of Agler-McCarthy and Amar concerning the Corona problem for the polydisk and the unit ball in $mathbb{C}^n$.
We establish that the Volterra-type integral operator $J_b$ on the Hardy spaces $H^p$ of the unit ball $mathbb{B}_n$ exhibits a rather strong rigid behavior. More precisely, we show that the compactness, strict singularity and $ell^p$-singularity of $J_b$ are equivalent on $H^p$ for any $1 le p < infty$. Moreover, we show that the operator $J_b$ acting on $H^p$ cannot fix an isomorphic copy of $ell^2$ when $p e 2.$
On the unit ball B^n we consider the weighted Bergman spaces H_lambda and their Toeplitz operators with bounded symbols. It is known from our previous work that if a closed subgroup H of widetilde{SU(n,1)} has a multiplicity-free restriction for the holomorphic discrete series of $widetilde{SU(n,1)}$, then the family of Toeplitz operators with H-invariant symbols pairwise commute. In this work we consider the case of maximal abelian subgroups of widetilde{SU(n,1)} and provide a detailed proof of the pairwise commutativity of the corresponding Toeplitz operators. To achieve this we explicitly develop the restriction principle for each (conjugacy class of) maximal abelian subgroup and obtain the corresponding Segal-Bargmann transform. In particular, we obtain a multiplicity one result for the restriction of the holomorphic discrete series to all maximal abelian subgroups. We also observe that the Segal-Bargman transform is (up to a unitary transformation) a convolution operator against a function that we write down explicitly for each case. This can be used to obtain the explicit simultaneous diagonalization of Toeplitz operators whose symbols are invariant by one of these maximal abelian subgroups.
For $-1<alpha<infty$, let $omega_alpha(z)=(1+alpha)(1-|z|^2)^alpha$ be the standard weight on the unit disk. In this note, we provide descriptions of the boundedness and compactness for the Toeplitz operators $T_{mu,beta}$ between distinct weighted Bergman spaces $L_{a}^{p}(omega_{alpha})$ and $L_{a}^{q}(omega_{beta})$ when $0<pleq1$, $q=1$, $-1<alpha,beta<infty$ and $0<pleq 1<q<infty, -1<betaleqalpha<infty$, respectively. Our results can be viewed as extensions of Pau and Zhaos work in cite{Pau}. Moreover, partial of main results are new even in the unweighted settings.