The Bohr radius for operator valued functions on simply connected domain

TL;DR

This paper extends classical Bohr inequalities to operator-valued holomorphic functions on simply connected domains, providing sharp bounds and generalizations including the Bohr-Rogosinski inequality and applications to $ u$-Bloch functions.

Contribution

It introduces improved and generalized Bohr inequalities for operator-valued functions, including sharp bounds and new results for $ u$-Bloch functions on various domains.

Findings

Established sharp improved Bohr inequalities for operator-valued holomorphic functions.

Generalized Bohr and Bohr-Rogosinski inequalities using sequences of non-negative functions.

Proved new Bohr inequalities for operator-valued $ u$-Bloch functions in different domains.

Abstract

In this paper, we first establish an improved Bohr inequality for the class of operator-valued holomorphic functions $f$ on a simply connected domain $\Omega$ in $\mathbb{C}$. Next, we establish a generalization of refined version of the Bohr inequality and the Bohr-Rogosinski inequality with the help of the sequence $\varphi=\{\varphi_n(r) \}^{\infty}_{n=0}$ of non-negative continuous functions in $[0,1)$ such that the series $\sum_{n=0}^{\infty}\varphi_n(r)$ converges locally uniformly on the interval $[0,1)$. All the results are proved to be sharp. Moreover, We establish the Bohr inequality and the Bohr-Rogosinski inequality for the class of operator-valued $\nu$-Bloch functions defined in two different simply connected domains, $\Omega$ and $\Omega_{\gamma}$, in $\mathbb{C}$.