Domination of semigroups on standard forms of von Neumann algebras

TL;DR

This paper characterizes when one semigroup dominates another on standard forms of von Neumann algebras, extending classical results to non-commutative $L^2$ spaces and considering positivity and non-reality.

Contribution

It extends Ouhabaz's semigroup domination characterization to non-commutative $L^2$ spaces and provides simplified criteria for positive semigroups.

Findings

Extended domination characterization to non-commutative $L^2$ spaces

Simplified criteria for positive semigroups

Considered non-real semigroups in the setting

Abstract

Consider $(T_t)_{t\ge 0}$ and $(S_t)_{t\ge 0}$ as real $C_0$-semigroups generated by closed and symmetric sesquilinear forms on a standard form of a von Neumann algebra. We provide a characterisation for the domination of the semigroup $(T_t)_{t\ge 0}$ by $(S_t)_{t\ge 0}$, which means that $-S_t v\le T_t u\le S_t v$ holds for all $t\ge 0$ and all real $u$ and $v$ that satisfy $-v\le u\le v$. This characterisation extends the Ouhabaz characterisation for semigroup domination to the non-commutative $L^2$ spaces. Additionally, we present a simpler characterisation when both semigroups are positive as well as consider the setting in which $(T_t)_{t\ge 0}$ need not be real.