This is an announcement for the paper "On the best constants in noncommutative Khintchine-type inequalities" by Uffe Haagerup and Magdalena Musat.
Abstract: We obtain new proofs with improved constants of the Khintchine-type inequality with matrix coefficients in two cases. The first case is the Pisier and Lust-Piquard noncommutative Khintchine inequality for $p=1$,, where we obtain the sharp lower bound of $\frac1{\sqrt{2}}$ in the complex Gaussian case and for the sequence of functions ${e^{i2^nt}}_{n=1}^\infty$,. The second case is Junge's recent Khintchine-type inequality for subspaces of the operator space $R\oplus C$,, which he used to construct a cb-embedding of the operator Hilbert space $OH$ into the predual of a hyperfinite factor. Also in this case, we obtain a sharp lower bound of $\frac1{\sqrt{2}}$,. As a consequence, it follows that any subspace of a quotient of $(R\oplus C)^*$ is cb-isomorphic to a subspace of the predual of the hyperfinite factor of type $III_1$,, with cb-isomorphism constant $\leq \sqrt{2}$,. In particular, the operator Hilbert space $OH$ has this property.
Archive classification: Operator Algebras; Functional Analysis
Mathematics Subject Classification: 46L52; 47L25
Remarks: 35 pages
The source file(s), UffeM2.tex: 125138 bytes, is(are) stored in gzipped form as 0611160.gz with size 33kb. The corresponding postcript file has gzipped size 224kb.
Submitted from: mmusat@memphis.edu
The paper may be downloaded from the archive by web browser from URL
http://front.math.ucdavis.edu/math.OA/0611160
or
http://arXiv.org/abs/math.OA/0611160
or by email in unzipped form by transmitting an empty message with subject line
uget 0611160
or in gzipped form by using subject line
get 0611160
to: math@arXiv.org.