Lack of isomorphic embedding from Lorentz function spaces into Lorentz operator ideals

Abstract

In the present paper, we study the existence of isomorphic embeddings from Lorentz function spaces $L_{p_1,q_1}$ into Lorentz ideals ${\mathcal{C}}_{p_2,q_2}$ in $B(H).$ In particular, we show that, for $p,q\in (0,\infty ),$ the quasi-Banach function space $L_{p,q}(0,1)$ isomorphically embeds into the ideal ${\mathcal{C}}_{p,q}$ if and only if $(p,q)=(2,2).$ This extends several existing results in the literature and answers a question due to Astashkin et. al.

to appear in Adv. Math