English

Hankel matrices acting on the Hardy space $H^1$ and on Dirichlet spaces

Complex Variables 2018-11-29 v3

Abstract

If μ\,\mu \, is a finite positive Borel measure on the interval [0,1)\,[0,1), we let Hμ\,\mathcal H_\mu \, be the Hankel matrix (μn,k)n,k0\,(\mu _{n, k})_{n,k\ge 0}\, with entries μn,k=μn+k\,\mu _{n, k}=\mu _{n+k}, where, for n=0,1,2,\,n\,=\,0, 1, 2, \dots , μn\mu_n\, denotes the moment of order n\,n\, of μ\,\mu . This matrix induces formally the operator Hμ(f)(z)=n=0(k=0μn,kak)zn\,\mathcal{H}_\mu (f)(z)= \sum_{n=0}^{\infty}\left(\sum_{k=0}^{\infty} \mu_{n,k}{a_k}\right)z^n\, on the space of all analytic functions f(z)=k=0akzk\,f(z)=\sum_{k=0}^\infty a_kz^k\,, in the unit disc D\,\mathbb D . When μ\,\mu \, is the Lebesgue measure on [0,1)\,[0,1)\, the operator Hμ\,\mathcal H_\mu\, is the classical Hilbert operator H\,\mathcal H\, which is bounded on Hp\,H^p\, if 1<p<\,1<p<\infty , but not on H1\,H^1. J. Cima has recently proved that H\,\mathcal H\, is an injective bounded operator from H1\,H^1\, into the space C\,\mathscr C\, of Cauchy transforms of measures on the unit circle. \par The operator Hμ\,\mathcal H_\mu \, is known to be well defined on H1\,H^1\, if and only if μ\,\mu \, is a Carleson measure and in such a case we have that Hμ(H1)C\mathcal H_\mu (H^1)\subset \,\mathscr C. Furthermore, it is bounded from H1\,H^1\, into itself if and only if μ\,\mu\, is a 11-logarithmic 11-Carleson measure. \par In this paper we prove that when μ\,\mu\, is a 11-logarithmic 11-Carleson measure then Hμ\,\mathcal H_\mu \, actually maps H1\,H^1\, into the space of Dirichlet type D01\,\mathcal D^1_0\,. We discuss also the range of Hμ\,\mathcal H_\mu\, on H1\,H^1\, when μ\,\mu \, is an α\alpha -logarithmic 11-Carleson measure (0<α<10<\alpha <1). We study also the action of the operators Hμ\,\mathcal H_\mu \, on Bergman spaces and on Dirichlet spaces.

Keywords

Cite

@article{arxiv.1804.02227,
  title  = {Hankel matrices acting on the Hardy space $H^1$ and on Dirichlet spaces},
  author = {Daniel Girela and Noel Merchán},
  journal= {arXiv preprint arXiv:1804.02227},
  year   = {2018}
}

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21 pages