Trigonometric chaos and ${\mathrm{X}}_p$ inequalities II -- ${\mathrm{X}}_p$ inequalities in group von Neumann algebras

Abstract

In the line of previous work by Naor, we establish new forms of metric ${\mathrm{X}}_p$ inequalities in group algebras under very general assumptions. Our results' applicability goes beyond the previously known setting in two directions. In first place, we find continuous forms of the ${\mathrm{X}}_p$ inequality in the $n$-dimensional torus. Second, we consider transferred forms of the sharp scalar valued metric ${\mathrm{X}}_p$ inequality in the von Neumann algebra $\mathcal{L}(\mathrm{G})$ of a discrete group $\mathrm{G}$. As a byproduct of our results, some metric consequences and their relation with bi-Lipschitz nonembeddability of Banach spaces are explored in the context of noncommutative $L_p$ spaces.

16 pages