$A$-spectral permanence property for $C^*$-algebras

Abstract

For a positive element $A$ of a $C^*$-algebra $\mathfrak{A}$, let ${\|X\|}_{A}$ denote the $A$-operator semi-norm of $X\in\mathfrak{A}$. In this paper, we aim to introduce and study the notion of $A$-spectrum for $X$ such that ${\|X\|}_{A}<\infty$. In particular when $A$ is well-supported, we establish an $A$-spectral permanence property for $C^*$-algebras.