Norm inequalities for the spectral spread of Hermitian operators

Abstract

In this work, we introduce a new measure for the dispersion of the spectral scale of a Hermitian (self-adjoint) operator acting on a separable infinite-dimensional Hilbert space that we call spectral spread. Then, we obtain some submajorization inequalities involving the spectral spread of self-adjoint operators, that are related to Tao's inequalities for anti-diagonal blocks of positive operators, Kittaneh's commutator inequalities for positive operators and also related to the arithmetic-geometric mean inequality. In turn, these submajorization relations imply inequalities for unitarily invariant norms (in the compact case).