New upper bounds for the numerical radius of operators on Hilbert spaces

摘要

Abstract This article presents some refinements and generalizations of existing numerical radius inequalities for Hilbert space operators. Further, several upper bounds for numerical radius with the Cartesian decomposition of an operator are provided. Also, we prove various upper bounds for the numerical radius of diagonal and off-diagonal operator matrices. Additionally, we establish certain numerical radius inequalities for operators using quadratic weighted operator geometric mean.