Elevating Precision in Inequalities for Numerical Radii and Operator Matrices

Abstract

In this paper, we aim to establish a range of numerical radius inequalities. These discoveries will bring us to a recently validated numerical radius inequality and will present numerical radius inequalities that exhibit enhanced precision when compared to those recently established for particular cases. Additionally, we employ the generalized Aluthge transform for operators to deduce a set of inequalities pertaining to the numerical radius. Moreover, we set forth various upper and lower bounds for the numerical radius of $2\times 2$ operator matrices, refining and expanding upon the bounds determined previously.