Some upper bounds for the Berezin number of Hilbert space operators


Ali Taghavi, Tahere Azimi Roushan, Vahid Darvish




In this paper, we obtain some Berezin number inequalities based on the definition of Berezin symbol. Among other inequalities, we show that if A, B be positive definite operators in B(H), and AB is the geometric mean of them, then ber 2 (AB) ≤ ber A 2 + B 2 2 − 1 2 inf λ∈Ω ζ(ˆ k λ), where ζ(ˆ k λ) = (A − B) ˆ k λ , ˆ k λ 2 , andˆkandˆ andˆk λ is the normalized reproducing kernel of the space H for λ belong to some set Ω,