English

An estimate for the numerical radius of the Hilbert space operators and a numerical radius inequality

Functional Analysis 2023-07-24 v1 Operator Algebras

Abstract

We provide a number of sharp inequalities involving the usual operator norms of Hilbert space operators and powers of the numerical radii. Based on the traditional convexity inequalities for nonnegative real numbers and some generalize earlier numerical radius inequalities, operator. Precisely, we prove that if \Ai,\Bi,\Xi\bh\A_i,\B_i,\X_i\in\bh (i=1,2,,ni=1,2,\cdots,n), mNm\in\N, p,q>1p,q>1 with 1p+1q=1\frac{1}{p}+\frac{1}{q}=1 and ϕ\phi and ψ\psi are non-negative functions on [0,)[0,\infty) which are continuous such that ϕ(t)ψ(t)=t\phi(t)\psi(t)=t for all t[0,)t \in [0,\infty), then \begin{equation*} w^{2r}\bra{\sum_{i=1}^{n}\X_i\A_i^m\B_i}\leq \frac{n^{2r-1}}{m}\sum_{j=1}^{m}\norm{\sum_{i=1}^{n}\frac{1}{p}S_{i,j}^{pr}+\frac{1}{q}T_{i,j}^{qr}}-r_0\inf_{\norm{x}=1}\rho(\xi), \end{equation*} where r0=min{1p,1q}r_0=\min\{\frac{1}{p},\frac{1}{q}\}, Si,j=\Xiϕ2\abs\Aij\XiS_{i,j}=\X_i\phi^2\bra{\abs{\A_i^{j*}}}\X_i^*, Ti,j=\Aimj\Biψ2\abs\Aij\Aimj\BiT_{i,j}=\bra{\A_i^{m-j}\B_i}^*\psi^2\bra{\abs{\A_i^j}}\A_i^{m-j}\B_i and ρ(x)=n2r1mj=1mi=1n\seqSi,jrξ,ξp2\seqTi,jrξ,ξq22.\rho(x)=\frac{n^{2r-1}}{m}\sum_{j=1}^{m}\sum_{i=1}^{n}\bra{\seq{S_{i,j}^r\xi,\xi}^{\frac{p}{2}}-\seq{T_{i,j}^r\xi,\xi}^{\frac{q}{2}}}^2.

Keywords

Cite

@article{arxiv.2307.11135,
  title  = {An estimate for the numerical radius of the Hilbert space operators and a numerical radius inequality},
  author = {M. H. M Rashid and Feras Bani-Ahmad},
  journal= {arXiv preprint arXiv:2307.11135},
  year   = {2023}
}

Comments

No comments