English

Remark Concerning Ces\'aro Operator on the Hardy Space $H^p(\mathbb{C}_+)$ in the Upper Half-Plane

Functional Analysis 2026-01-06 v1

Abstract

We consider Ces\'aro operator on the Hardy space Hp(C+)H^p(\mathbb{C}_+) in the upper half-plane for 1<p<1<p<\infty. In \cite{AS} it was proved that for all 1<p<1<p<\infty the spectrum of the operator V=2(p1)pCIV=\frac{2(p-1)}{p}C-I is located on the unit circle and in \cite{ABC1} the authors of this note showed that for p=2p=2 operator VV is unitary. In the present note we show that for 1<p<1<p<\infty, p2p\ne 2, the norm of the operator VV is strictly greater than one.

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Cite

@article{arxiv.2601.01201,
  title  = {Remark Concerning Ces\'aro Operator on the Hardy Space $H^p(\mathbb{C}_+)$ in the Upper Half-Plane},
  author = {Valentin V. Andreev and Miron B. Bekker and Joseph A. Cima},
  journal= {arXiv preprint arXiv:2601.01201},
  year   = {2026}
}